Content uploaded by Boris Schiffer
Author content
All content in this area was uploaded by Boris Schiffer on Jul 08, 2015
Content may be subject to copyright.
June 2015 | Volume 9 | Article 3441
REVIEW
published: 24 June 2015
doi: 10.3389/fnhum.2015.00344
Frontiers in Human Neuroscience | www.frontiersin.org
Edited by:
Hauke R. Heekeren,
Freie Universität Berlin, Germany
Reviewed by:
Timm B. Poeppl,
University of Regensburg, Germany
Stuart Brody,
Charles University, Czech Republic
*Correspondence:
Tillmann H. C. Kruger,
Department of Psychiatry, Social
Psychiatry and Psychotherapy,
Hannover Medical School,
Carl-Neuberg-Strasse 1, Hannover
D-30625, Germany
krueger.tillmann@mh-hannover.de
†Gilian Tenbergen and
Matthias Wittfoth have contributed
equally to this work.
Received: 15August2014
Accepted: 29May2015
Published: 24June2015
Citation:
TenbergenG, WittfothM, FrielingH,
PonsetiJ, WalterM, WalterH,
BeierKM, SchifferB and KrugerTHC
(2015) The neurobiology and
psychology of pedophilia: recent
advances and challenges.
Front. Hum. Neurosci. 9:344.
doi: 10.3389/fnhum.2015.00344
The neurobiology and psychology of
pedophilia: recent advances and
challenges
Gilian Tenbergen1†, Matthias Wittfoth1†, Helge Frieling2, Jorge Ponseti
3, Martin Walter
4,
Henrik Walter
5, Klaus M. Beier
6, Boris Schiffer
7 and Tillmann H. C. Kruger
1*
1 Division of Clinical Psychology and Sexual Medicine, Department of Psychiatry, Social Psychiatry and Psychotherapy,
Hannover Medical School, Hannover, Germany, 2 Laboratory for Molecular Neuroscience, Department of Psychiatry, Social
Psychiatry, and Psychotherapy, Hannover Medical School, Hannover, Germany, 3 Department of Sexual Medicine, University
Hospital Schleswig-Holstein, Kiel, Germany, 4 Clinical Affective Neuroimaging Laboratory, Medical Faculty University Hospital
Magdeburg, Magdeburg, Germany, 5 Division of Mind and Brain Research, Charité – University Clinic Berlin, Berlin, Germany,
6 Institute of Sexology and Sexual Medicine, Charité – University Clinic Berlin, Berlin, Germany, 7 Division of Forensic Psychiatr y,
Department of Psychiatry, Psychotherapy, and Preventive Medicine, LWL-University Hospital Bochum, Bochum, Germany
A pedophilic disorder is recognized for its impairment to the individual and for the harm
it may cause to others. Pedophilia is often considered a side issue and research into the
nature of pedophilia is delayed in comparison to research into other psychiatric disorders.
However, with the increasing use of neuroimaging techniques, such as functional and
structural magnetic resonance imaging (sMRI, fMRI), together with neuropsychological
studies, we are increasing our knowledge of predisposing and accompanying factors
contributing to pedophilia development. At the same time, we are faced with methodolog-
ical challenges, such as group differences between studies, including age, intelligence,
and comorbidities, together with a lack of careful assessment and control of child sexual
abuse. Having this in mind, this review highlights the most important studies investigating
pedophilia, with a strong emphasis on (neuro-) biological studies, combined with a brief
explanation of research into normal human sexuality. We focus on some of the recent
theories on the etiology of pedophilia such as the concept of a general neurodevelopmental
disorder and/or alterations of structure and function in frontal, temporal, and limbic brain
areas. With this approach, we aim to not only provide an update and overview but also
a framework for future research and to address one of the most signicant questions
of how pedophilia may be explained by neurobiological and developmental alterations.
Keywords: pedophilia, child sexual abuse, functional and structural MRI, neuropsychology, neurodevelopment,
etiology, epigenetic, neurobiology
Introduction
In the light of frightening and emotionally disturbing sexual oenses against children, experts have
focused more on the level of sexual behavior, referred to subsequently as “oenses,” while not dif-
ferentiating the causes for that behavior in an appropriate and adequate way. Concerning sexual
oending against children, two groups can be distinguished: rst, those who show no sexual pref-
erence disorder, but whom, for various reasons, sexually abuse children. Reasons include sexually
inexperienced adolescents, mentally retarded persons, and those with antisocial personality disorders
(ASPDs), or perpetrators within general traumatizing family constellations, which seek surrogate
June 2015 | Volume 9 | Article 3442
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
partners in children (Rice and Harris, 2002; Greenberg etal., 2005).
ese individuals are most likely diagnosed with various impulse-
control disorders, accounting for their engaging in child sexual
abuse (CSA) without a specic sexual preference for prepubescent
children (Allnutt etal., 1996; Greenberg etal., 2005). Second, there
are those who do display a sexual preference disorder, namely
pedophilia (i.e., the sexual preference for prepubescent minors)
and/or hebephilia (i.e., the sexual preference for pubescent minors)
(Seto etal., 1999).
Although this preference increases the risk of engaging in CSA,
only about 50% of all individuals who do sexually abuse children
are pedophilic (Blanchard etal., 2001; Schaefer etal., 2010) and
not every pedophilic individual actually has abused children. e
other 50% of individuals that have abused children are those who
do so without a sexual attraction to children; i.e., they lack the
necessary social skills to develop and maintain emotional and
sexual relationships with appropriately aged peers and look to
“replacement partners” in children as a kind of “surrogate” (Beier,
1998; Seto, 2008; Mokros etal., 2012b).
Overall, there is great consensus regarding the negative con-
sequences for victimized children. e number of known cases
of CSA in Germany, for example, was on average 14,600 in the
last 5years (Bundeskriminalamt, 2012). e estimated incidence
is far greater than what is reported to authorities. In the United
States, the National Center for Victims of Crimes, as reported
in Finkelhor etal. (2009), states that one in 5 girls and one in
20 boys are victims of CSA (Crimes, 2012). Additionally, CSA
has important economical aspects. e estimated burden for the
particular countries is enormous, including childhood health care
costs, adult medical costs, productivity losses, criminal justice
costs, and special education costs, which results in an estimated
lifetime cost per victim of non-fatal child maltreatment in general
of $210,000 in the USA (Fang etal., 2012).
In this article, we discuss pedophilia with a focus on recent
ndings of the denition, neuropsychology, and neurobiology
(including neuroimaging) of pedophilia as a specic phenotype
within the spectrum of human sexual preference. For that purpose,
the article highlights the current gaps in literature and oers sug-
gestions as to where the eld of pedophilia research should head
in order to close these gaps.
Pedophilia and Pedophilic Disorder:
A Psychological Perspective
Classication of Pedophilia
Pedophilia is dened as an ongoing sexual attraction toward pre-
pubertal children (Freund, 1963, 1967; Seto, 2009). In the new
DSM-5, pedophilia is de-pathologized by dierentiating between
the sexual preference for prepubescent children (i.e., pedophilia)
and the disorder in case of additional factors. ese factors include
experiencing signicant distress and impairment by fantasies and
urges, or the acting out on behavioral level, including child pornog-
raphy consumption and/or committing hands-on CSA oenses.
e estimated prevalence leads to questions about the diagnos-
tic validity and reliability of pedophilia as a classication entity.
According to the DSM-5, pedophilic sexual preference and the
pedophilic disorder must be dierentiated. As can be seen in
Table1 , the behavioral criterion was not included in the DSM-5 as
a specier, though it holds relevance for researchers and clinicians.
From a clinical point of view, both child pornography consump-
tion and/or hands-on CSA oenses would count as preference
behaviors (Seto, 2010; First, 2011).
From a clinical perspective, it is necessary to stress that there
are pedophilic men who restrict their desire for sexual contact with
children to fantasies only, and other men who are at risk to commit
an oense because fantasy alone does not satisfy their sexual desire.
is second group is potential oenders who wish to reduce their
increasingly overwhelming impulses with therapeutic help (Beier
etal., 2009a,b; Schaefer etal., 2010; Wakeeld, 2012). It is possible
for these men to be diagnosed with Pedophilic Disorder – due to
experiencing interpersonal distress – without them committing
an oense.
e other group of pedophilic men includes those who have
committed sexual oenses against children. ese individuals may
feel remorse (and seek help to avoid a relapse), while others do
not. Note that both fulll criterion B of the DSM-5, as shown in
Table1 , means that it has to be diagnosed as Pedophilic Disorder.
Furthermore, it is necessary to distinguish between the exclusive
type of pedophilia (attracted only to children) and non-exclusive
type, and whether the person is attracted to males, attracted to
females, or to both.
It is a completely dierent situation for perpetrators who com-
mitted sexual oenses against children, which were not caused
by a pedophilic preference. ose are the surrogate types of sex
oenders and can be diagnosed within the category of impulse-
control disorder, accounting for the lack of a sexual preference for
children but the committed act of CSA (DSM-5: 312.89; ICD-10:
63.8). Moreover, most sexual assaults happen in the “Dunkelfeld”
for approximately every reported case of CSA; another ve are le
unreported, suggest some scholars (Hall and Hall, 2007; S eto, 2009).
Dunkelfeld is a German word that literally translates to “dark eld.”
It is of great importance for clinical diagnosis whether or not an
erotic preference for the body scheme of children on the fantasy-
level exists. ere is a high chance that this information would be
given voluntarily by self-referred, self-motivated pedophilic men,
but less likely by those who are already involved with the legal
system (probation etc.). It is therefore essential for the assessment
TABLE 1 | Diagnostic criteria of a pedophilic disorder according to
DSM-5.
DSM-5 pedophilic disorder
Over a period of at least 6months, recurrent,
intense sexually arousing fantasies, sexual
urges, or behaviors involving sexual activity with
a prepubescent child or children (generally age
13years or younger)
Specify if:
Sexually attracted to males
Sexually attracted to females
Sexually attracted to both
The fantasies, sexual urges, or behaviors cause
clinically signicant distress or impairment in
social, occupational, or other important areas of
functioning
Specify if:
Limited to Incest
The person is at least age 16years and at
least 5years older than the child or children in
Criterion A
Specify type:
Exclusive type (attracted only
to children)
Non-exclusive type
June 2015 | Volume 9 | Article 3443
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
and a reliable diagnosis to obtain a cooperation/compliance level.
In self-motivated pedophiles, this collaboration is highest and
makes them a highly interesting target group for research (see
Section “Methods for Diagnosing Pedophilia”).
is underlines that pedophilia as a sexual preference must
be seen independently from sexual oending against children –
otherwise there would be only oending pedophiles. From a
research point of view, it is imperative to understand in what way
the neurobiological conditions – notwithstanding sexual prefer-
ence – encourage the sexual behavior. ese are possibly the same
mechanisms that also encourage oense-like behavior in men with
other sexual preferences (for instance in the case of rape on the
background of sexual preference for adult women). Additionally,
research eorts have to unravel which neurobiological mechanisms
determine and regulate sexual preference, and how preference and
behavior are interconnected.
In the research domain, pedophilia is currently viewed as a phe-
notype of sexual preference within the realm of human sexuality,
including various dierent phenotypes (e.g., the sexual orientation
toward the same gender), only that it concerns a preferred age in
addition to gender (Beier etal., 2009a,b; Schaefer etal., 2010).
is is separate from, but in addition to, behavioral manifestations
including the use of child pornography and the commitment of
child sexual oenses (Beier etal., 2009a,b; Neutze etal., 2011).
Consequently, the sexual preference itself cannot be considered
a mental disorder similar to how a homosexual orientation was
considered in the 1970s in the United States of America (Green,
2002). Separating sexual preference from psychosocial impair-
ment, thus allowing for the practice of various sexual behaviors
with consenting partners, has been applied within the new DSM-5
with the other paraphilias as well, including fetishism, bondage/
dominance-sadism/masochism, and is therefore not specic to
pedophilia (Wright, 2010, 2014).
Epidemiology of Pedophilia
e most commonly asked question about pedophilia is how
frequently it occurs. Obtaining reliable incidence numbers of
pedophilia as a preference disorder is dicult as individuals are
typically unwilling to admit pedophilic preferences, particularly
when oenses have been committed. e prevalence of a true
pedophilic sexual preference is approximately 1%, but when
general fantasies are investigated, that prevalence can reach up to
5% among men in the general population, extrapolated from the
studies discussed below.
Some studies suggest that the prevelance of pedophilia may
be between 3% and 5% in the general population (as reviewed by
Seto, 2009). In penile plethysmography studies of men with sexual
oense histories against children, these prevalences can jump from
30% for men with one oense to 61% for men with 3 or more sexual
oenses against children (Blanchard, 2010; Seto, 2009).
A rst population-based study concerning this issue was based
on the Berlin Male Study (BMS), in which the prevalence of erectile
dysfunction, its age-dependency, and its relation to general health
variables as well as quality-of-life measures were determined in
6000 men, aged 40–79 (Schäefer etal., 2003; Englert etal., 2007).
A total of 1915 men took part in the rst phase of this study. ese
men were then invited to further participate in a comprehensive
sexological study by responding to an extensive questionnaire on
sexual experiences and behavior. e outcome was a sample of
373 men, of whom 63 were single and 310 were in a relationship.
Fiy-seven percent of the questioned men recognized at least one
paraphilia-associated arousal pattern as part of their fantasies,
46.9% of this group used them for arousal enhancement during
masturbation, and 43.7% acted out these patterns in a relationship.
e nding of relevance here is that 3.8% acted out a pedophilic
preference on the behavioral level – which means of these men – 14
men acted out their impulses toward children. Taking these 14
cases into account, the prevalence of a pedophilic sexual preference
in Germany can be extrapolated to approximately 3.8% in the worst
case (calculated based on the selected sample of 373 men) (Ahlers
etal., 2011). However, pedophilia was not strictly assessed in this
sample; thus, this prevalence should be interpreted with caution.
Much higher is the prevalence in an older anonymous self-
report survey study of 193 healthy male college students: 21%
admitted some degree of sexual interest in children, 9% admitted
to having sexual fantasies involving children, 5% admitted to
masturbating to orgasm through these fantasies, and 9% admitted
that they would have sex with a child, if it were guaranteed they
would never be caught (Briere and Runtz, 1989). Yet, it is important
to note that this study did not specically investigate the preference
of pedophilia, rather sampled fantasy.
Considering the lack of reliable estimates of the prevalence of
pedophilia in general, prevalence estimates for the subtypes of
pedophilia also remain scarce. e current estimated prevalence
of homosexual pedophilia is anywhere between 9 and 40% (Hall
and Hall, 2007); the ratio of heterosexual to homosexual pedophiles
was approximately 1.4:1 among men with CSA oenses in another
study using phallometry (Freund and Watson, 1992). Prevalence
estimates of bisexual pedophilia are not yet available due to meas-
urement complexity (Hall and Hall, 2007).
Although pedophilia is generally regarded as a phenomenon in
males (Seto, 2008), victim surveys show that a female perpetrator
was indicated by between 14 and 24% of sexually abused males
and by between 6 and 14% of sexually abused females (Green,
1999). In a Dutch report (Wijlman et al., 2010) investigating
female sex oenders in the Netherlands between 1994 and 2005,
common characteristics included intellectual impairment, a high
current and/or lifetime prevalence of psychiatric or personality
disorders, and a high lifetime prevalence of neglect and sexual
abuse. Frequently, the abuse against a child is carried out in col-
laboration with a male partner or victims are seen as surrogates
to replace less than desirable relationships. Currently, there is no
reliable estimate of pedophilia in women and the question remains
whether pedophilia, as currently dened, even exists in women.
Methods for Diagnosing Pedophilia
e most important method for ascertaining the phenotype of
sexual preference is the clinical exploration. In this process, the
content of sexual fantasies during masturbation is particularly
signicant as it reveals gender preferences, body scheme age of
the “partner,” and favored practices. Here, it is possible to assess
the sexual preference structure in detail including the dierentia-
tion between exclusive and non-exclusive types of pedophilia and
hebephilia (Beier etal., 2013). If the legal system is involved, the
patient might not (or only partially) cooperate due to the possibility
of new accusations.
June 2015 | Volume 9 | Article 3444
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
For assessment of body scheme age preference, the ve Tanner
stages have proven useful. ey describe the process of physiologi-
cal maturing by focusing on the development of the secondary
sex characteristics from 1 (prepubescent) to 5 (adult). erefore,
Tanner stage 1 concerns the prepubescent developmental phase,
displaying a complete lack of secondary sex characteristics showing
no facial or pubic hair, no penile or scrotal enlargement in males,
no breast development or pubic hair growth in females. Tanner
stage 2 corresponds to the onset of breast budding in females and
testicular enlargement in males. Tanner stage 3 depicts the breast
and areola development in females, continued testicular growth
and initial penile lengthening in males. Tanner stage 4 corresponds
to increased breast and areola growth, initial separation from sur-
rounding breast tissue in females, and in males testicular volume
increases, scrotum darkens, penile elongation continues. Tanner
stage 5 represents full maturity, complete breast development, and
separation from surrounding breast tissue in females, full penile
growth and scrotum darkness, and testicular volume in males, and
full pubic hair coverage in both (Marshall and Tanner, 1969, 1970).
Please refer to Figure1 for a visual explanation of Tanner stages
and their relationship to sexual preference. e Tanner stages can
be very useful during the exploration of sexual preference and are
an essential component of the diagnostic procedure in various
treatment and research programs (Seto, 2008). Pedophilia is here
dened as the erotic attraction to a prepubescent body scheme
corresponding to Tanner stages 1 and 2 (Blanchard, 2010).
Child pornography use is also strongly related to pedophilia. As
a study deriving from the German Dunkelfeld Prevention Project
FIGURE 1 | Tanner scales of males and females as used in sexual
preference assessment. Image credit: Michał Komorniczak, 2009,
CC-BY-SA. Tanner Scale Male: http://goo.gl/7cxTLM. Tanner Scale Female:
http://goo.gl/haB9Cb, both accessed June 09, 2015.
concluded, among 345 pedophiles admitting one or more sexual
oenses against children, 37% have solely used child pornography,
21% committed exclusively hands-on sexual contacts with a minor,
and 42% have committed both (Neutze etal., 2012).
e most well-known objective method of measuring pedo-
philic interest is penile plethysmography (PPG) or phallometry.
is method measures genital sexual arousal through sexual
stimuli and is based on the relative change in penile response.
Sexual preference can be determined as the relative change in
penile response to various classes of sexual stimuli (according to
Tanner scales), such as prepubescent, pubescent, or adult, female,
or male targets. At least one of these classes should correspond to
the individual’s stated or inferred sexual preference. ere are two
dierent methods of phallometry, circumferential and volumetric.
e circumferential method measures intra-individual changes in
penile girth through a wire band tted around the base of the
penis in response to diering classes of sexual stimuli (Ba nc ro
etal., 1966). e volumetric method uses a glass tube tted around
the penis to measure calibrated air output as a result of erection
(Freund, 1963). e latter method is sensitive to small changes,
making it useful when assessing partial- or non-admitters, or pedo-
philic men that attempt to hide their sexual preferences (Freund
and Blanchard, 1989; Blanchard etal., 2001). Both measures are
valid and reliable, producing sensitivities between 55 and 61% and
specicities between 95 and 96% (Kuban etal., 1999; Blanchard
etal., 2001; Hughes, 2007).
Self-reported interest in children, child pornography use, and
the number of children as sexual victims all uniquely contribute to
phallometrically assessed sexual interest in children (Mokros etal.,
2012b). Additionally, child pornography users showed a greater
phallometric response to sexual child stimuli than non-pedophilic
child sexual oenders (CSO), and there was no signicant dier-
ence within the child pornography group between those who had
committed sexual oenses against children and those who had
not (Seto etal., 2006).
While phallometry has long been the ‘gold standard’ in assess-
ing sexual preferences, other methods have been developed using
indirect and implicit tests to cope with faking responses. One of the
more strongly validated tests is the viewing time paradigm meas-
uring the length of time a participant spends looking at specic
images as an indicator for sexual preference. Research assumes that
all participants, including CSO, will look signicantly longer at
sexually arousing stimuli (Mokros etal., 2012a). An initial study by
Abel showed a high specicity and sensitivity to classifying sexual
oenders against adolescent boys (98% control vs. 90% oender),
only moderate sensitivity for those against boys under 14 (98 vs.
76%), and lower performance against adolescent/young girls (77
vs. 91%) (Abel etal., 1994). A follow-up study found that between
the viewing time paradigm and the PPG, discriminatory capacity
was negligible, showing no signicant dierences in their abilities
to discriminate among sex oenders with deviant sexual interest
in adolescent females, adolescent males, female children, or male
children (Abel etal., 1998). Abel etal. (1998) suggested, however,
that the PPG may be slightly better at classifying oenders against
young boys, although this claim needs urgent replication.
e pictorial Stroop was developed as a modied, sexual version
of the original Stroop task, measuring implicit sexual associations
June 2015 | Volume 9 | Article 3445
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
that exert their eects automatically, which are dicult if not
impossible to control consciously. Research supports its use among
a sample of CSO (n=24) compared to controls (n=24), with those
admitting deviant sexual interest in children having the greatest
mean bias for child stimuli as compared to adult stimuli (partial
η2=0.07) (Ciardha and Gormley, 2012). However, other factors
could have contributed to the results, justifying a need for further
renement. Results in a separate study of 35 men, 11 of who were
homosexual and 24 were heterosexual, reporting no history of
child sexual oenses indicated a discriminatory ability between
heterosexual men and homosexual men using female stimuli,
but could not discriminate among preferred ages. e authors
suggested that other mechanisms are responsible for rating child
stimuli, thus decreasing the validity for this test among pedophilic
participants (Bourke and Gormley, 2012).
Eye tracking and pupil dilation may also indicate sexual prefer-
ence and results show that men react more strongly in these studies
than women. Heterosexual men did initially orient to their stated
preference and eye xations were signicantly longer than when
looking at non-preferred stimuli (Fromberger etal., 2012b). In a
study investigating pedophilia, eye tracking produced high sen-
sitivity and specicity, 86.4 and 90.0%, respectively (Fromberger
etal., 2012a). Heterosexual women reacted similarly to stimuli
of both sexes, whereas heterosexual men, homosexual men, and
homosexual women reacted most strongly to their stated partner
gender in pupil dilation research (Rieger and Savin-Williams,
2012). However, criticisms have been put forward suggesting that
the success seen in heterosexual and homosexual participants to
respective stimuli in pupil dilation studies is attributable to factors
other than sexual preference, such as luminance, salience of the
stimuli, and emotional reaction (Beatty and Lucero-Wagoner,
2000; Rieger and Savin-Williams, 2012). ese methods have not
yet been used in the sexual age preference measurement of pedo-
philes, but do hold promise as collateral information for diagnosis.
e aforementioned methods are not without their aws,
such as test–retest reliabilities or the ability to fake results. ese
methodological dierences have led to interest of using specic
functional Magnetic Resonance Imaging (fMRI) techniques in
order to classify pedophilic interest (Ponseti etal., 2012). Results
have shown that a preference-specic BOLD pattern is evident,
which can be potentially used as a diagnostic tool. Keeping these
ndings in mind, this methodology could be used in the future
as a classication paradigm.
Co-Morbidities with Pedophilia
Pedophilia does not always occur in isolation; men with pedophilia
oen have extensive histories of psychiatric disorders that, in
extreme cases, can overshadow discovery of etiological course.
Whether this is a secondary phenomenon that relates to emotional
and social consequences of this preference, or whether these are
true co-morbidities remains elusive.
Kramer (2011) addresses a point that currently many pedophilia
researchers are facing: should we continue to classify pedophilia
as a separate psychiatric disorder or as a sexual orientation, when
patients harbor complaints not only of the preference but of the
pressure under which they suer? is pressure oen precedes
the onset of psychiatric illness (most oen mood or anxiety
disorders), which then precedes the decision to seek psychiatric
help (Kramer, 2011). Due to a temporal-causal relationship being
nearly impossible to determine in these cases, the DSM-5 has
dierentiated among those who experience the sexual preference
but do not suer and those who do, leading us back to Pedophilia
vs. Pedophilic Disorder, regardless of whether or not child sexual
oenses have occurred (Kramer, 2011).
A relationship has been identied between pedophilia and co-
morbid psychiatric disorders. Among pedophiles in residential or
outpatient treatment, two-thirds had a lifetime history of mood or
anxiety disorders, 60% had lifetime substance abuse history, with
51% naming alcohol as their drug of choice, and 60% qualied for
a personality disorder diagnosis of which obsessive-compulsive
(25%), antisocial (22.5%), narcissistic (20%), and avoidant (20%)
were most common, as reported in reviews (Fagan etal., 2002;
Green, 2002). Kalichman (1991) investigated 144 sexual oenders
divided into child, adolescent, and adult oenders (although not
controlled for pedophilic preference) for state and trait measures of
anger, anxiety, self-esteem, and various measures on the Minnesota
Multiphasic Personality Inventory (MMPI). Findings demon-
strated that child oenders, as compared to oenders against
adolescents and oenders against adults, scored signicantly
higher on 2 out of 3 scales for the “neurotic” triad (hypochondriasis
and hysteria), and 3 out of 4 scales for the “psychotic tetrad” (para-
noia, psychasthenia, schizophrenia), and were signicantly more
introverted (Kalichman, 1991). ese ndings suggest that child
sexual oending is characterized by emotional disturbance and
higher rates of psychopathology. Moreover, these ndings do not
necessarily mean that there is a direct connection to pedophilia.
In an empirical study comparing 20 forensic inpatients with
pedophilia attracted to males or attracted to females (but lacking
information of whether they were exclusive or non-exclusive types,
respectively) and 24 matched male controls on various psychiatric
measures, ndings included increased personality subscale scores
from the MMPI-2 for psychopathy and paranoia, with enhanced
scores for hypochondriasis, depression, hysteria, and masculinity/
femininity, psychasthenia, schizophrenia, and social introversion
(Kruger and Schier, 2011). Furthermore, that study shows that
61.1% of the sample qualied for a personality disorder diagnosis,
with Borderline Personality Disorder (22%; from Cluster B) and
Avoidant Personality Disorder (33%; from Cluster C) as the two
most common (Kruger and Schier, 2011). Self-report results in low
socioeconomic status individuals, oen including non-pedophilic
sexual oenders against children and rapists, indicate more social
anxiety, less social poise, and a decreased ability to appropriately
socially assert oneself, relating to the cognitive distortions seen
among these groups of negative attitudes toward women, reinforc-
ing beliefs about sex with children, denial of harm to victims, and
misattribution of responsibility of oending (Geer etal., 2000).
ese results indicate that delinquent pedophiles seem to
dier from healthy controls (HC) for Axis I and II psychiatric
comorbidity development. However, it remains to be further
explored whether these alterations are linked specically to the
sexual preference of pedophilia or to the commitment of sexual
oenses against children, as meant by the behavioral criterion of
Pedophilic Disorder (impaired control over sexual impulses) or
a combination of both.
FIGURE 2 | Overview of neuropsychological ndings in pedophilia and
child sexual offending.
June 2015 | Volume 9 | Article 3446
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Neuropsychological Findings Associated with
Pedophilia
Aside from psychiatric comorbidities, neuropsychological altera-
tions are another important issue, which have been addressed by
several studies, and may further contribute to the understanding
of the development and course of pedophilia. e majority of stud-
ies in the following paragraphs were conducted as uncontrolled
studies, mostly using incarcerated CSO, which were not carefully
screened for incarceration stress or for pedophilic sexual prefer-
ence. erefore, the results are not generalizable and need careful
consideration.
Initial studies exploring the neuropsychological correlates of
pedophilia oen used uncontrolled designs with incarcerated
pedophilic men. An initial study by Tarter et al. (1983) among
recently incarcerated adolescent oenders and controls, no
neuropsychological dierences were found among the groups on
the Wechsler Adult Intelligence Scale (WAIS) or Pittsburgh Initial
Neuropsychological Test System. Furthermore, among incarcerated
adult male sex and non-sex non-violent oenders, no dierences
were seen in any neuropsychological test variables, aer age and
education status were accounted for (Abracen etal., 1991). Keeping
in mind that the subject groups were incarcerated at the time of
study and that pedophilia was not explicitly examined, the results
are limited in their generalizability and specicity to pedophilia.
In another study, heterosexual and homosexual pedophiles were
tested, but each group, plus one control group, had sexual oense
histories and were incarcerated at the time of the study. Fully admit-
ting, heterosexual pedophiles had gender dierentiation indices
(or the erotic sensitivity for the gender-dierentiating body shapes
that distinguish physically mature males and females), which were
greater than for non-admitting heterosexual pedophiles, but no
dierences were found for either homosexual or bisexual pedo-
philes. is highlights that fully admitting heterosexual pedophiles
prefer the body shapes of female children, whereas the partial- or
non-admitting pedophiles do not seem to discriminate between
victim body types (Freund etal., 1991; Freund and Kuban, 1993).
Gillespie and McKenzie (2000) investigated neuropsychological
dierences among forensically incarcerated sex oenders and
non-sex oenders and found no signicant dierences on any
of their measures, including the WAIS, Trail Making Task, List
Learning test, Controlled Oral Word Association test, and National
Adult Reading Task (NART). Among personality disordered
oenders, violent sex oenders, violent non-sex oenders, and
non-violent, non-sex oenders, no dierences were noted on
any neuropsychological test variables, including the WAIS, Trail
Making Task, Face Recognition, Wechsler Memory Scale-Revised,
and Wechsler Recognition Memory Task (Dolan etal., 2002). As
with previous studies, neither incarceration status nor sexual
preference was controlled for, which limits the generalizability
results to pedophilic men.
Within a heterogeneous group of 20 sexual oenders (not dif-
ferentiated by gender or age preference), executive functions were
signicantly impaired; however, the generalization of these nd-
ings to pedophilia is limited considering the nature of the group
(Joyal etal., 2007). Findings included prolonged Stroop eects
(reaction time dierences between incongruent and congruent
trials: 77.2 vs. 59.4s) that were indicative of stronger interferences
and impaired verbal skills, with decits seen in verbal uency and
in verbal processing and memory. While response inhibition and
sustained attention showed impairments, set shiing, cognitive
exibility, and visuo-spatial integration abilities were normal.
In a more controlled study that dierentiated among pedophilic
CSO with a primary sexual interest in prepubescent children
(n=20) and non-pedophilic CSO with a primary sexual inter-
est in adults (n=20) and controls (n=20), Suchy etal. (2009)
investigated patterns of executive function. Non-pedophilic
oenders showed general impairments, whereas among pedophilic
oenders, decits were more specic. Both groups showed decits
in executive functions, specically showing slower information
processing speeds for pedophilic oenders and semantic knowl-
edge impairments in non-pedophiles (Suchy etal., 2009, 2014).
Eastvold etal. (2011) corroborated these results, further specifying
that although pedophilic (incarcerated) oenders (n=30) do not
show generalized executive functioning impairments, they instead
show a distinct pattern of dierences, not all of which are worse
than that for control participants, characterized by impaired per-
formance on behavioral inhibition measures (partial η2=0.129),
but better performance in abstract reasoning measures and plan-
ning measures (partial η2=0.132) as compared to non-sexual
oender (n=29) and non-pedophilic sexual oender controls
(n=30). A further study also found specic decits in inhibition in
15 pedophilic oenders as compared to non-sexual oenders and
non-oender controls, whereas more global executive functioning
impairments were seen in non-pedophilic child molesters (Schier
and Vonlaufen, 2011). Yet, new ndings are showing that pedo-
philic men are characterized by a distinct neurocognitive weak-
ness, performing worse than controls on measures of behavioral
inhibition and information processing (Suchy etal., 2014), but
do not have a more planning-oriented response style as found by
Eastvold and colleague (Habermeyer etal., 2013b). Please refer to
Figure2 for an overview of neuropsychological impairments seen
in non-pedophilic and pedophilic child sex oenders.
Despite these results, further research has indicated contra-
dictory results regarding executive functioning impairments.
June 2015 | Volume 9 | Article 3447
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
For example, heterosexual formerly incarcerated pedophiles
scored lower than controls in the Wechsler Adult Intelligence
Scale-Revised (WAIS-R) vocabulary subtest measuring verbal
fluency, but performances on tests measuring impulsivity or
attention capabilities were all normal: Wisconsin Card Sorting
Task (WCST), Trail Making Task A and B, Gambling Test, Stroop
Color-Word Test, and Controlled Oral Word Association test
(Cohen etal., 2002). In a study using a shortened version of the
WAIS-R known as the WIP, the WCST, the d2 Attention Deficit
Test, and the Corsi Block-Tapping Test showed that – unlike the
Cohen study (Cohen etal., 2002) – convicted pedophiles serving
prison sentences in a forensic treatment facility had impaired
performance on all subtests of the WIP except for completing
images (Kruger and Schiffer, 2011). The participants consisted
of both exclusive heterosexual and homosexual pedophiles.
Significantly weaker performance on the d2 Attention-Deficit
Test was also seen, but this difference disappeared once par-
ticipant age was controlled. The Corsi Block-Tapping test and
the WCST, however, showed normal performances among the
pedophilic offender group. Cantor etal. (2005), in their meta-
analysis of IQ data in sex offenders, found not only that lower
IQ between 90 and 95 was associated with sexual offending
against children and with pedophilia specifically, but also that
the younger the victim, the lower the IQ of the offender.
ese results suggest that disturbed and prosecuted pedo-
philes do show decits in executive functioning, which might be
due rather to mental disturbances and not to the sexual prefer-
ence. is is in contrast to ndings from the APSD/psychopathy
literature that suggests, at least among community samples
measured for psychopathic traits, that these personality traits
are linked to decits in response inhibition and impulsivity,
specically with social deviancy associated with overall decits
in executive functioning and response inhibition, whereas
callous-unemotional traits observed in psychopathy are asso-
ciated with improved executive functioning abilities (Sellbom
and Verona, 2007). In ASPD, broad executive function domain
decits have been noted in response inhibition, planning, and
rule acquisition, and reversal learning, suggesting that previous
studies examining pedophilia may have been measuring ASPD
or simply an incarceration stress eect in their incarcerated
samples rather than pedophilia. is is in contrast to recent stud-
ies that have found processing speed impairments in pedophiles,
but few other decits suggestive more of oense status eects
than sexual preference eects (Eastvold etal., 2011; Kruger and
Schier, 2011; Schier and Vonlaufen, 2011; Suchy etal., 2014).
Future studies need to carefully control for psychiatric comor-
bidities, incarceration status, and oender status, as no research to
date has examined neuropsychological decits in potential oend-
ers or non-oending pedophiles. Only with these studies will the
true nature of neuropsychological impairment be illustrated.
Neurobiology and Neurodevelopment of
Pedophilia
Introduction and Conceptual Framework
Research regarding the etiology of pedophilia suggests the view of
a complex and multifactorial phenomenon in which the inuences
of genetics (Blanchard etal., 2007), stressful life events, specic
learning processes (Jespersen etal., 2009a), as well as perturbations
in the structural integrity of ‘pedophilic’ brains may generate this
specic phenotype of a sexual preference (Schier etal., 2007;
Schiltz etal., 2007; Cantor etal., 2008). Initial theories relied mainly
upon psychological mechanisms to account for a pedophilic
preference, including classical and operant conditioning, as the
behavioral mechanism through which the ‘abused-abuser’ theory
by Freund etal. (1990) and Freund and Kuban (1994) could be
explained as well as attachment style in childhood as a marker
for dysfunctional cognitive sexual schemas in adulthood (Beech
and Mitchell, 2005).
e rst theories to account for sexual behavior disorder associ-
ated with pedophilia suggested masturbatory conditioning [e.g.,
Laws and Marshall (1990)] or childhood sexual abuse (Freund
etal., 1990; Fedoro and Pinkus, 1996) as causal explanations.
However, as Seto purports, due to lack of stringent methodol-
ogy that includes proper control groups, small experimental or
treatment eect sizes, and lacking knowledge of eect duration,
these theories are not well supported. Beyond this, the majority of
victims are female, whereas the majority of oenders are male, and
if conditioning were the only logical theory to explain the etiology
of pedophilia, it stands to reason that there would be more female
pedophiles than are clinically seen (Seto, 2008; Jespersen etal.,
2009b). However, a study by Klucken etal. (2009) showed that men
are more easily conditioned through exposure to sexual stimuli
than are women, casting signicant doubt on the conditioning
theory as it applies to female pedophiles. Currently, there is a
strong push to understand the brain’s role in sexual preference
development, particularly as it relates to pedophilia.
As discussed in a previous review by Seto (2008), there are
three major neurobiological theories, which have come to be
connected to pedophilia but all have the same shortcoming that
they rely on data based on cases of pedophiles who have other
psychological disorder diagnoses, are incarcerated or otherwise
legally sanctioned, or are not suciently diagnostically classied
(i.e., not dierentiating between the exclusive or the non-exclusive
type, etc.).
e rst is the “frontal lobe” theory that refers to orbitofrontal
and le and right dorsolateral prefrontal cortex dierences that are
oen seen in pedophilic men (Graber etal., 1982; Flor-Henry etal.,
1991; Burns and Swerdlow, 2003; Schier etal., 2007, 2008a,b).
As the orbitofrontal cortex is responsible for behavior control
(Bechara etal., 2000; O’Doherty etal., 2003), especially inhibiting
sexual behavior, volume dierences or dysfunction in this area may
explain the sexual behavior disorder associated with pedophilia,
although not pedophilic sexual preference.
e second major theory is the “temporal lobe” theor y, referring
to reports of hypersexuality accompanying pedophilia. Studies
have shown that disturbances of the temporal lobes can result in
an increase in pedophilic behaviors or an increase in the breadth of
deviant sexual interests (Hucker etal., 1986; Langevin etal., 1988).
ese disturbances include temporal lesions and hippocampal
sclerosis (Mendez etal., 2000). Ponseti noticed further dieren-
tial temporal lobe activations in pedophilic men that highlight
a hypersexuality-specic activation prole, further supporting
the role of the temporal lobe in the expression of hypersexuality
June 2015 | Volume 9 | Article 3448
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
that is oen seen with sexual behavior disorders (Schiltz etal.,
2007; Ponseti etal., 2012). However, this t heory also does not fully
explain the etiology of the preference.
e third major neurobiological theory holds that dierences
in the sex dimorphic brain structures aected by the masculini-
zation of the male brain would more strongly aect pedophilia
development. Furthermore, the volumes of these structures would
be inuenced, but the hypothesis failed to state in what direction
these changes occur, i.e., either increased or decreased volumes as
a result of testosterone exposure. In the frontal and temporal lobes,
these dierences would be limited to those sexually dimorphic
structures, rather than a generalized dierence in region volume,
but research has not supported the hypothesis (Cantor etal., 2008).
Furthermore, there is an additional theory that combines the
frontal and temporal lobe theories. It states that the frontal and
temporal lobes aect pedophilic sexual preference expression
and its associated behaviors dierently, with the frontal lobe
(orbitofrontal and dorsolateral prefrontal cortices) accounting for
committing the sexual oenses against children and the temporal
lobe (amygdala and hippocampus) accounting for the sexual
preoccupation with children oen seen in pedophilic men (Seto,
2008, 2009; Poeppl etal., 2013).
Currently, pedophilia is oen viewed as an interaction among
neurodevelopmental factors based on genes and the (inutero-)
environment as previously discussed (Becerra García, 2009). is
theory holds that pedophilic sexual preference is a neurodevel-
opmental disorder corroborated by increased rates of non-right-
handedness, shorter stature, lower intelligence, head injury,
prenatal androgen levels, and the associated neuronal structural
and functional dierences that are present since childhood and/
or adolescence. e exact directions of these relationships to
pedophilic sexual preference, committing child sexual oenses,
or consuming child pornography are still to be disentangled. ere
is currently no causal evidence yet to support a role in pedophilic
sexual preference development.
Neurodevelopmental Correlates of Pedophilia
e prevailing perspective among biologists was that sex dier-
ences are linked solely to the exposure to testosterone inutero [see
Phoenix etal. (1959) and Ehrhardt and Meyer-Bahlburg (1979)].
e masculinization of an initially undierentiated human female
brain is caused by testosterone’s induction of organizational eects
during a limited period of time, as extrapolated from animal
research. Sexual dierentiation and development of subsequent
sexual preference are likely an interplay between the impact of
sex chromosomes on gene expression and sex hormones (Bao
and Swaab, 2010). In pedophilia, research investigating biologi-
cal dierences is underway and studies have already highlighted
structural and functional dierences. e following is a discussion
of ndings that are classied as neuropsychological; however, the
onset of these dierences is inutero, childhood, and adolescence,
thus suggesting that these ndings are actually a part of human
development and contribute to pedophilic preference onset rather
than acting as consequences thereof.
As a group consisting of primarily incarcerated individuals,
pedophilic men show a doubled rate of head injuries before age 13,
though aer 14years of age the dierence is no longer signicant,
highlighting possible causative eects in multiple areas of cognitive
functioning. While prenatal perturbations inuence cognitive
functioning and disorder development, so can head injuries result-
ing in unconsciousness in childhood, especially before age 13years
(Blanchard etal., 2002, 2003). is is a result of cortical develop-
ment plasticity during childhood, when synaptic myelination and
pruning are at their peak (Zhong etal., 2013). Of 725 originally
tested, 685 pedophilic men participated in a study investigating
the role of head injuries with associated loss of consciousness
in pedophilia development. Pedophilic participants reported a
signicantly higher number of head injuries that resulted in a loss
of consciousness prior to age 13 than did non-pedophilic child
sexual oender participants. ese results also positively correlated
with a diagnosis of attention decit-hyperactivity disorder and
le-handedness among pedophilic participants.
More importantly, the more child victims each pedophile had
correlated positively with each additional head injury before age
13, but not those sustained later in adolescence or adulthood
(Blanchard etal., 2003). However, no studies have yet been con-
ducted investigating head injuries in non-incarcerated pedophilic
men with histories of CSA, or those with no such histories. Also
lacking are studies on the prevalence of head injuries in children
in general, as well as for the number of children with head injuries
who subsequently go on to commit sexual oenses against children
in adulthood.
e organizational–activational hypothesis was initially devel-
oped by Phoenix and his colleagues in the 1950s in consequence to
observations that a temporary rise in prenatal and early post-natal
testosterone shapes development by masculinizing and defemi-
nizing neural networks in males, whereas the absence thereof
results in the development of female-typical neural phenotype
(Phoenix etal., 1959; Schulz etal., 2009). According to the organi-
zational–activational hypothesis, pre- and perinatal as well as
pubertal/adolescent androgens are able to shape cortical circuits
(organization), whereas in adults androgens can only modulate
the activity of these circuits (activation). e process of sexual
dierentiation occurs between weeks 12 and 18 of prenatal life
and during the rst 2months aer birth, periods during which
testosterone has organizational eects on the brain. During this
time, not only behavior is programed, depending on the level of
exposure to testosterone, but also handedness, total digit length,
and second to fourth nger length ratios (George, 1930; Rahman,
2005). ese neuroendocrinological developmental dierences
are then activated during puberty and their relationship to
pedophilia development will be discussed further in the coming
paragraphs.
In understanding the relationship between testosterone, the
brain, sexual behavior, and the rise of sexual deviancy, one must
rst understand how testosterone inuences the brain. In verte-
brates, androgen receptors (ARs) can be found in several brain
regions, including the lateral septum, posteromedial bed nucleus
of the stria terminalis (BNSTpm), medial preoptic nucleus of the
hypothalamus, ventral premammillary nucleus, ventromedial
nucleus of the hypothalamus, and the medial amygdaloid nucleus,
otherwise found in the temporo-occipital, superior-parietal, and
orbitofrontal cortices (Wood and Newman, 1999; Jordan etal.,
2011a).
June 2015 | Volume 9 | Article 3449
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Research has shown a relationship between prenatal androgen
exposure and hand preference in pedophilic men with a history
of sexual oending against children. ese men show a trend for
increased rates of sinistrality – more ecient use of the le side/
hand and is preferred – whereas hebephilic men show increased
rates of ambiguous-handedness (Fazio etal., 2014) as compared
to teleiophiles, and this has been discussed as an indicator of
developmental perturbations resulting from a lack of prenatal
testosterone exposure (Cantor etal., 2004). Homosexuality has
also been associated with a higher prevalence of le-handedness
(Cantor, 2012), and it would be of interest to see whether the
higher prevalence of le-handedness seen among pedophilic men
is attributable to pedophilia specically or to a higher rate of homo-
sexuality within this population as compared to teleiophilic men.
More specically, approximately 11% of the general non-oender
population is non-right-handed, whereas pedophilic men with
histories of sexually oending against children are approximately
15% non-righthanded, this dierence being signicant (Bogaert,
2001; Cantor etal., 2004, 2005; Blanchard etal., 2007; Rahman
and Symeonides, 2008). Future studies should control for sexual
orientation (homosexuality vs. heterosexuality) when examining
handedness in pedophilia.
ese eects also inuence the second to fourth nger length
ratio (D2:D4) (Voracek etal., 2007), a marker altered also in other
psychiatric disorders including alcohol dependence (Lenz etal.,
2012). e D2:D4 ratio is smaller in men than in women and
is used as an indirect marker of prenatal testosterone exposure
(Beaton et al., 2011). Additional dierences in sexual orienta-
tion exist, such that the D2:D4 ratio is smaller in homosexual
women compared to heterosexual women, as well as homosexual
men compared to heterosexual men (Williams etal., 2000; Rahman
and Wilson, 2003; R ahman, 2005; Manning etal., 2007). Although
prenatal testosterone exposure aects both hand preference and
D2:D4 ratio, the data here are equivocal and no rm conclusions
have been drawn regarding the absolute relationship between hand
preference and D2:D4. However, exposure to prenatal testosterone
does not aect the D2:D4 ratio between 9weeks gestation and
birth, in contrast to hand preference, where dierences are noted
here and possibly aer puberty (Lenz etal., 2012). How this applies
to pedophilia is currently under investigation.
e following markers of neurodevelopmental abnormality
have also been implicated in the neurodevelopmental processes
contributing to pedophilia: sibling sex composition, maternal
and paternal age at birth, and the uctuating asymmetry of nger
lengths and wrist widths. Pedophiles have a greater number of older
brothers (Lalumière etal., 1998; Côté etal., 2002). Greater paternal
age at birth was related to an increased chance of homosexual-
ity, whereas greater maternal age increased risk for pedophilia,
specically (rather than generalized paraphilia) (Rahman and
Symeonides, 2008).
Considering the eects of neurodevelopmental perturbations
and executive functioning on pedophilia development, it seems
worthwhile to consider the eect of intelligence. Research results
have been contradictory: for example, generalized sexual delin-
quency is related to lower intelligence, whereas among groups of
non-sexual oenders, pedophiles, and non-pedophiles, neither
education level nor intelligence diered signicantly. However,
when pedophilic participants were separated by use of child
pornography, those who had no history of child pornography use
showed a decreased IQ and lower mean education level as compared
to those who did (Briken etal., 2006; Blanchard etal., 2007; Schier
and Vonlaufen, 2011). e main caveat to this research is that child
pornography is considered a reliable indicator of pedophilic sexual
interest, therefore confounding any results found with education or
intelligence level because those pedophiles with child sexual oense
histories are also more likely to have used child pornography (Seto,
2010). Research is currently focusing on the role of intelligence
among pedophilic men who have only consumed child pornog-
raphy and those who have committed CSA oenses, particularly
dierentiating those who have been incarcerated from those who
have not (Babchishin etal., 2011; Seto etal., 2011, 2012).
As these results indicate, pedophiles do seem to dier from
HC on neurodevelopmental measures. However, these results
are varied and few strong conclusions can be drawn, including
increased rates of le-handedness and increased rates in head
injuries before age 13. e next section will discuss the relationship
of neurological and neurobiological dierences to the development
of pedophilia, as both are the focus of current research determining
the neural correlates of pedophilia. Please refer to Tab le 2 for a
summarization of neuroimaging ndings in pedophilia.
Structural Brain Alterations in Pedophilia
For the purposes of this review, we focused on providing an over-
view of recent neuroimaging work in pedophilia research starting
in 2007, with case studies from 2000 to 2003. is was done for
space and readability reasons; such that another recently published
review provides an excellent in-depth discussion of neuroimag-
ing in pedophilia (Mohnke etal., 2014). at review summarizes
the state of the art of neuroimaging in pedophilia as being in its
infancy, with a general consensus that ndings are scattered and
need to be replicated. Most results from neuroimaging studies
in pedophilia have found neurostructural or neurofunctional
correlates of CSA, not pedophilia perse. e amygdala remains a
region of high interest, but Mohnke etal. (2014) suggest stricter
methodology to replicate these ndings. Our discussion parallels
and expands upon the aforementioned review.
A famous case study that highlighted a neurological disease
that caused impulsive sexual behavior and could have been an
expression of an underlying pedophilic orientation was a right
orbitofrontal tumor in a 40-year-old man (Burns and Swerdlow,
2003). Prior to the discovery of his tumor, the patient had overtly
claimed no sexual interest in children, but aer the tumor pro-
gressed, he made sexual advances to his prepubescent stepdaughter
and began a pornography collection, including child pornography,
resulting from impulse control loss associated with orbitofrontal
cortex dysfunction. Although his behavior was non-exclusive and
his preference was not explicitly tested, the most striking fact about
his symptoms is that all pedophilia-like symptoms disappeared
aer resection of the tumor. Even more, aer the tumor recidivated,
the pedophilia-like symptoms remerged and disappeared again
aer the second resection, thus showing a clear causal link between
behavior and brain function. However, the clear majority of orbito-
frontal tumors do not result in pedophilic behavior, meaning this
case study should be interpreted cautiously.
TABLE 2 | Findings from previous neuroimaging studies in pedophilia.
Author
(year)
Method Structural/
functional
PPT groups (n) Paradigm/
software
Correction Threshold/
Sig
Findings
Schiffer
etal. (2007)
MRI Frontostriatal
and cerebellum
structure
Heterosexual (9)
and homosexual
pedophiles (9)
VBM-whole
brain/SPM 2
FDR (whole
brain)/FWE
corrected within
ROIs
p<0.05 GM volume reductions in pedophiles: PHc L/R,
IFG L/R, OFC L/R, Ins L/R, Cer L/R; Cin L/R,
Posterior Cin L, STG L/R, MiTG R, Pcu L/R, Put
L/R (Amy L/R in unpublished re-analysis)Heterosexual (12)
and homosexual
(12) controls
Schiltz etal.
(2007)
MRI Amygdala
structure
Pedophilic (15)
Community
controls (15)
VBM/manual
morphometry/
SPM2 ROIs/
MRIcro
FWE/corrected
for multiple
comparisons
within ROIs
p<0.05 GM reductions in pedophiles: Amy R, Hyp L/R, SI
L/R, Septal Region R, Bed Nucleus
Striae Terminalis L/R
Enlargement of Temporal Horn R
Poeppl etal.
(2013)
MRI Prefrontal cortex
and amygdala
structure
Heterosexual (2)
and homosexual (7)
pedophiles
VBM 8
toolbox/SPM 8
FWE corrected
within ROIs
p<0.05 GM volume decreases in pedophiles: only in Amy
R; pedosexual interest and sexual recidivism
associated with GM volume decreases in insular
cortex and DLPFC L, preference for younger
children associated with GM decreases in the
OFC and Ang L/R
Heterosexual (11)
controls
Cantor etal.
(2008)
MRI White matter
structure
Pedophiles (44)
Teleiophilic sexual
offenders (21)
VBM whole
brain/SPM 2
FDR p<0.05 Reduced WM volumes in pedophiles in Superior
Fronto-Occipital Fasciculus L, Arcuate Fasciculus R
Parcelation
with ANIMAL
No differences in GM
Non-sexual
Offender (53)
Cantor and
Blanchard
(2012)
MRI White matter
structure
Pedophiles (19) VBM Whole
brain/SPM 2
Not specied p<0.05 Reduced WM volumes in Temporal Lobe L/R
and Parietal Lobe L/R in pedophiles/hebephiles
compared to teleiophiles
Hebephiles (49)
Teleiophiles (47)
Cohen etal.
(2002)
PET Frontal and
temporal
function
Heterosexual
pedophiles (7)
Auditory
stimulus/
software not
specied
Bonferroni p<0.05 No differences seen in glucose metabolism after
an erotic auditory paradigm; lower metabolism in
ITC and in Superior VFG during neutral auditory
condition in pedophiles compared to controls; no
survival after correction
Community
controls (7)
Dressing
etal. (2001)
fMRI Orbitofrontal
function
Homosexual
pedophiles (1)
Visual stimuli
block design/
brain voyager
Not specied Not specied Stronger recruitment in pedophiles in response to
erotic pedohomosexual stimuli: ACC, Brain Stem
R, PFC R, Basal Ganglia R, OFC RControls (2)
Walter etal.
(2007)
fMRI Hypothalamus
and lateral
prefrontal cortex
function
Pedophiles (13) Visual stimuli/
SPM2
Uncorrected p<0.005 Decreased activations in pedophiles to
sexual>emotional arousal contrast: DLPFC R
(Precentral), DLPFC R (MFG/SFG), DLPFC L
(SFG), Occipital Cortex L
Controls (14)
Schiffer etal.
(2008a)
fMRI Frontal and
temporal
function
Homosexual
pedophiles (11)
Visual stimuli/
SPM2
Whole brain
analysis
uncorrected/
false discovery
rate
p<0.001/
p<0.05
Stronger Activations in pedophiles compared
to controls in contrast nude children/
adults>dressed children/adults: Fus L/R, HC
L/R, Tha R
Homosexual
matched
controls (10)
Schiffer etal.
(2008b)
fMRI Amygdala
function
Heterosexual
pedophiles (8)
Visual sexual
stimuli/SPM2
Whole brain
analysis
uncorrected/
FDR
p<0.001/
p<0.05
Activations seen in pedophiles compared
to controls in contrast nude children/
adults>dressed children/adults: MFG R,
ACC L/R
Heterosexual
matched
controls (12)
Sartorius
etal. (2008)
fMRI Amygdala
function
Homosexual
pedophiles (10)
Visual stimuli/
SPM2
Uncorrected p<0.005 Activation in pedophiles to children (Boys/
girls)<neutral geometric stimuli contrasts in
Amy R Heterosexual
controls (10)
Poeppl etal.
(2011)
fMRI Cortical and
subcortical
function
Heterosexual (2)
and homosexual (7)
pedophiles
Visual sexual
stimuli/SPM5
Whole brain
analysis
uncorrected/
FWE/FDR
p<0.001/
p<0.05
Activations in pedophiles compared to controls
in contrast nude children>scrambled images of
children: MFG R, Ins L/R, MTG R, IPL L, Pos R,
MCC R, PCC R, HC R, Tha L, Cer RHeterosexual
non-sexual offender
controls (11)
(Continued)
June 2015 | Volume 9 | Article 34410
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Author
(year)
Method Structural/
functional
PPT groups (n) Paradigm/
software
Correction Threshold/
Sig
Findings
Ponseti
etal. (2012)
fMRI Pattern
classication
function
Heterosexual (11)
and homosexual
(13) pedophiles
Heterosexual (18)
and homosexual
(14) controls
Visual stimuli;
pattern
classication/
SPM8
Uncorrected p<0.001/
p<0.001
Deactivations in homosexual pedophiles
compared to controls in boys<men contrast:
Cer L/R, Lin L/R, Anterior Tha L, HC R, Occ L,
Fus L, ITG R, Ang R
Deactivations in heterosexual pedophiles
compared to controls in girls<women contrast:
NC L/R, SPG L/R, ITG L/R, Fus L/R, Cin L, Occ
L, Amy L, Ins L, IFG R, Tha L, Cer R
Habermeyer
etal.
(2013a)
fMRI Function Heterosexual
pedophiles (8)
Erotic sexual
stimuli/brain
voyager 2.3.0
Uncorrected/
cluster-level
threshold
correction
p<0.005/
p<0.05
Activations in pedophiles in sex×age×group
voxel-wise ANOVA analysis in MiFG R
Heterosexual
controls (8)
Kärgel etal.
(2015)
rsfMRI Function Pedophiles+
CSA (12)
Pedophiles−
CSA (14)
Healthy Controls
(14)
SPM8 and
rsfMRI toolkit
REST
Uncorrected
at voxel level;
Family wise
error corrected
at cluster level
p<0.005/
p<0.05
DMN: (P-CSA>P+CSA) Diminished
connectivity to left MSF, left OFC. No differences
in opposite contrast (P+CSA>P-CSA).
(HC>P+CSA): VM PFC, OFC. No differences in
P+CSA>HC contrast
Limbic Network: (P-CSA>P+CSA) diminished
connectivity between L Amy and VM PFC,
ACC, OFC, anterior PFC. No differences in
P+CSA>P-CSA. In HC>P+CSA contrast:
increased connectivity between L Amy and L
anterior/inferior PFC, L Lin. No differences in
P+CSA>HC contrast
Poeppl etal.
(2015)
rsfMRI Function Heterosexual (2)
and homosexual (7)
pedophiles
Meta-analytic
connectivity
modeling
(MACM) and
ALE
FEW at cluster
level
p<0.05 Seed area: R Amy connected to HC, R ventral
striatum, R Tha, L Amy, L Cla, L hyp, L Put, L HC,
L Mid, L Tha for psychosexual arousal
Heterosexual (11)
controls
L DLPFC: L Ant Ins, DMPFC, L Per, L SPL,
L VLPFC for cognition and perception, spec.
working memory
L Ins: L PaO, L Ant Ins, L Pos, L STG, L Put, R
PaO, R STG, R DLPFC/Ant Ins, R Put, R pMC, L
Tha, R Tha, L Ext for perception and cognition
ACC, anterior cingulate cortex; Amy, amygdala, Ang, angular gyrus, Cau, caudate, CC, corpus callosum; Cer, cerebellum; Cin, cingulate gyrus; Cla, claustrum; DLPFC, dorsolateral
prefrontal cortex; Ext, extrastriate cortex; FPPFC, frontopolar prefrontal cortex (Brodmann area 10); Fus, fusiform gyrus; HC, hippocampus; Hyp, hypothalamus; IFG, inferior
frontal gyrus; Ins, insula; IPL, inferior parietal lobule; ITC, inferior temporal cortex; ITG, inferior temporal gyrus; L/R, left/right; Lin, lingual gyrus; MCC, middle cingulate cortex; MFG,
medial frontal gyrus; MSF, medial superior frontal; Mid, midbrain; MiFG, middle frontal gyrus; MOG, middle occipital gyrus; MTG, middle temporal gyrus; NC, nucleus caudatus;
Occ, occipital lobe; OFC, orbitofrontal cortex; PaO, parietal operculum; Par, paracentral lobule; PCC, posterior cingulate cortex; Pcu, precuneus; Per, peristriate cortex; PHc,
parahippocampal gyrus; Pos, post central gyrus; Pre, precentral gyrus; PSS, posterior cingulate cortex; Put, putamen; SFG, superior frontal gyrus; SI, substantia innominata; SPG,
superior parietal gyrus; SPL, superior parietal lobule; SOG, superior occipital gyrus; STG, superior temporal gyrus; Tha, thalamus; VFG, ventral frontal gyrus.
TABLE 2 | Continued
June 2015 | Volume 9 | Article 34411
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
A further publication with two case studies highlights the role
of the temporal cortex in regulating sexual behavior (Mendez
et al., 2000). In the rst case, a 60-year-old man developed
fronto-temporal dementia and presented with increased sexual
drive the molestation of extrafamilial children. e second case
was a 67-year-old man who developed hippocampal sclerosis
that similarly increased his sexual desire. He attempted to molest
extrafamilial children. Both patients sexually abused their own
young children, suggesting a latent predisposition to pedophilic
behaviors existed in these patients prior to disease onset. Both
patients showed hypometabolism of the right temporal lobe as
measured with FDG-PET. Aer treatment with antidepressants
(paroxetine for the former patient and sertraline for the latter),
a decrease in pedophilic behaviors and desires was reported
(Mendez etal., 2000). ese ndings support that dysfunction
in the prefrontal cortex may prompt a latent predisposition to
sexual attraction to children through disinhibition, whereas a
dysfunction in the temporal cortex might elicit this response
through sexual preoccupation (Jordan etal., 2011b). is does
not explain the etiology of pedophilia as a sexual preference but as
an acquired hypersexual behavioral disorder, and furthermore one
that rarely presents in the realm of fronto-temporal dementia and
hippocampal sclerosis. Clear here is the expression of pedophilic
behaviors resulting from the neurological diagnoses, but not why
these behaviors were pedophilic rather than hypersexual in nature.
For further discussion of dementia and its relation to hypersexual/
pedophilic disorders, please refer to Mohnke etal. (2014).
Only a handful of studies of MRI-based structural dierences
in pedophilia have been published so far. By means of voxel-based
morphometry (VBM), several alterations of gray matter (GM)
and white matter (WM) were found. In 18 incarcerated exclusive
heterosexual and homosexual pedophilic men with histories of
sexual oending against prepubertal children, a signicantly lower
GM volume in the bilateral orbitofrontal cortex, bilateral insula,
June 2015 | Volume 9 | Article 34412
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
bilateral ventral striatum (putamen), precuneus, le posterior
cingulate, as well as superior and right middle temporal, parahip-
pocampal gyrus, and in the cingulate compared to 24 teleiophiles
was found. ese ndings were corrected for multiple comparisons
using the false discovery rate within the whole brain (Schier
etal., 2007). However, only the le parahippocampal gyrus would
have remained signicant had a Bonferroni correction for the 15
additional ROI analyses been applied. e authors proposed a
theoretical frontal-executive dysfunction and suggested that –
similarly to obsessive-compulsive spectrum disorders – these
ndings may form a neurophysiological circuit contributing to
the pathophysiology of pedophilia.
In another study with 15 pedophilic forensic inpatients in
comparison to a healthy teleiophile group, GM reductions were
found in four pre-dened ROIs comprised of right amygdalae;
in right septal region, the bed nucleus striae terminalis (BNST),
hypothalamus, and the substantia innominate bilaterally (Schiltz
etal., 2007). Later on, amygdalar volume reduction was conrmed
by a posthoc manual volumetric analysis, unpublished until now
(Schiltz, personal communication). ese results could be related
to a developmental hypoplasia and underscores the inuence of
right amygdalar lateralization on regulation of sexual behavior,
supporting the temporal lobe hypothesis of pedophilia.
One study was published showing that, in comparison to non-
sexual oender controls (n=11), convicted pedophilic oenders
(n=9) show only GM volume decreases in the centromedial nuclei
group of the right amygdala which extended into the lateroba-
sal nuclei group and the cornu ammonis of the hippocampus,
although this nding did not survive correction for the large
number of predened ROIs (Poeppl etal., 2013). Interestingly,
pedosexual interest, including the strength of such interest, and
sexual recidivism were associated with GM volume decreases in the
le insular and dorsolateral prefrontal cortices, while preference
for younger children was associated with GM decreases in the
orbitofrontal cortex and bilateral angular gyri (Poeppl etal., 2013).
What the studies of Schier etal. (2007) and S chiltz etal. (2007)
have in common is a comparison between a group of sentenced sex
oenders recruited from forensic institutions with healthy teleio-
philes without criminal histories, leading to potential confounds in
the results with factors other than pedophilia, such as criminality
or stress of imprisonment. However, an advantage of the study
by Schier etal. (2007) is that they included only pedophiles of
the exclusive type, allowing for interpretations including sexual
preference.
By comparing 44 pedophilic men with histories of sexually
oending against children or child pornography consumption,
with 53 men with histories of non-sexual oenses, dierences were
found in the WM only, highlighting a bilateral connection route
traveling the superior fronto-occipital fasciculus, as well as a right-
sided alteration in the arcuate fasciculus. No dierences in GM
were observed (Cantor etal., 2008). ese ndings were upheld
in a follow-up conrmatory reanalysis (Cantor and Blanchard,
2012) and interpreted as insucient connectivity in pedophilic
individuals, rather than simply GM reductions in disparate (sub-)
cortical regions (Cantor and Blanchard, 2012).
Studies to date contain shortcomings either due to the sample
sizes, to the conguration of the control group, or because the
methodology of VBM was used in a restricted way by focusing on
apriori regions of interest. e take home message of the present
structural imaging MRI studies of pedophilia is that while there
have been dierent results from dierent studies, one nding has
been replicated across studies: reduced right amygdala volumes in
pedophiles compared to teleiophilic controls (Mendez etal., 2000;
Schier etal., 2007; Schiltz etal., 2007; Poeppl etal., 2013). is
nding supports the temporal lobe theory of pedophilia referred to
in Section “Introduction and Conceptual Framework.” Diusion-
tensor imaging is a method of WM imaging that holds promise to
validate and expand previous VBM results.
Functional Brain Alterations in Pedophilia
Only a few functional imaging studies have been conducted to
investigate possible dierences during the processing of sexual
stimuli in the brains of pedophiles. With only one exception, they
were visual sexual stimulation studies, thereby inducing a strong
visual bias while making this modality the dominant model of
perceptual processing alterations in paraphilias, although sensory
systems oer potential other routes to sexual responsiveness.
However, with the background of recent evidence explaining how
hetero- or homosexual teleiophilic brains process visual sexual
information and regulate the psychosexual and physiosexual
components of sexual arousal [please refer to Safron etal. (2007),
Georgiadis and Kringelbach (2012), Stoléru et al. (2012), and
Poeppl etal. (2014)] for a deeper discussion), it is a reasonable
step toward the understanding of pedophilia to study whether
there are functional dierences in the brain network associated
with sexually arousing visual pictures of children.
Research has highlighted alterations in pedophiles through
positron emission tomography (PET) and functional MRI. For
example, in a PET study of pedophilia, a decreased regional cerebral
metabolic rate for glucose was found in the right inferior temporal
cortex and superior frontal gyrus, without Bonferroni correction.
is rate decreased in the pedophilic group aer presentation of
girl and women cues, whereas it increased in the teleiophilic group
(Cohen etal., 2002). e authors interpreted this as a consistent
brain abnormality underlying decreased glucose metabolism in
the temporal and frontal cortices implicated in cortical regulation
of sexual arousal. e small sample size of seven participants in
each group limits the generalizability and condence with which
the results can be interpreted.
In fMRI research, the rst study that included a single homo-
sexual pedophile found increased activity of the anterior cingulate
gyrus, right prefrontal cortex, and basal ganglia in response to
pictures of minimally clothed boys, regions that comprise the
attentional brain network with the right orbitofrontal cortex
(Dressing etal., 2001).
Decreased activations were seen in the hypothalamus, dorsal
midbrain, dorsolateral prefrontal cortex, and right lateral parietal,
right ventrolateral, and right occipital cortices, as well as in the
le insula in 13 hetero- and homosexual forensic pedophiles
when viewing sexual stimuli as compared to emotional stimuli
as compared to teleiophiles (Walter etal., 2007). Based on these
ndings, it was suggested that the missing sexual interest toward
adults could be explained by impairment in subcortical regions
associated with the autonomic component of sexual arousal, i.e.,
June 2015 | Volume 9 | Article 34413
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
lack of activation seen in hypothalamus and dorsal midbrain in
pedophilia. Additionally, using a regression analysis approach, the
activation in the le DLPFC was inversely correlated with the score
on the child abuse subscale of the multiphasic sexual inventory
(MSI), indicating also possible alterations of cognitive processing
of sexual stimuli in these subjects (Schier etal., 2008a,b).
Homosexual and heterosexual incarcerated pedophiles were
examined with fMRI to determine whether there were dier-
ences associated with age and child gender preference. Among
homosexual pedophiles with a history of sexual oenses against
children (n=11) in comparison with homosexual (n=12) con-
trols, the substantia nigra, caudate nucleus, the occipitotemporal
and prefrontal cortices, thalamus, globus pallidus, and the striatum
were activated in response to male child sexual stimuli, whereas
these were not among the matched homosexual teleiophiles
(Schier etal., 2008a). is was interpreted as an increased eort
in evaluating respective stimuli in pedophilic compared to control
participants. In another investigation, heterosexual pedophiles
(n=8), when compared to heterosexual teleiophiles (n=12), aer
presentation with female child sexual stimuli displayed signicant
activations in the amygdala, hippocampus, substantia nigra, cau-
date nucleus, the medial dorsal thalamic nucleus, and the inferior
temporal gyrus, suggesting a similar response pattern to sexually
preferred stimuli as seen in healthy heterosexual males (Schier
etal., 2008b). Pedophilic males showed a signal increase only in
the right dorsolateral prefrontal cortex in response to the preferred
sexual stimuli (no activation was seen in the control group to sexual
stimuli of adult women). An interesting nding was that whereas
the healthy male teleiophiles activated the orbitofrontal cortex in
response to both sexually explicit adult female and female child
imagery, this activation was not seen among male pedophiles. All
together, the authors suggest that orbitofrontal deactivation, as
shown in pedophilic participants, represents a dysfunction of the
neural network necessary for the appropriate cognitive component
of sexual arousal processing.
ere were also attempts to investigate the perception and
emotional processing of visual sexual stimuli. For example, the
right amygdala showed greater activation in homosexual pedo-
philes when they were presented with male child sexual stimuli
compared to heterosexual male teleiophiles who observed female
adult sexual pictures, although the participants were not matched
for sexual orientation, thus potentially obscuring true ‘pedophilic’
activations (Sartorius etal., 2008). e authors interpreted this
increased amygdala activation to stimuli depicting children that
were observed in pedophiles as a possible fearful emotional reac-
tion combined with sexual arousal, supported by the lack of an
appropriate amygdala activation to adult female stimuli (Sartorius
etal., 2008).
Poeppl et al. (2011) used a block design in their study to
investigate sexual interest in pedophiles (nine pedophiles with a
history of contact oenses and 11 non-sexual oender controls)
that consisted of male and female nude Tanner scale imagery,
including Tanner scales I, III, and V, corresponding to prepubes-
cent, pubescent, and adult images. Results of whole brain analyses
showed signicantly greater activation in the middle temporal lobe,
hippocampus, posterior cingulate cortex, thalamus, medial frontal
lobe, and culmen of the cerebellum in pedophiles to the Tanner
I>neutral contrast. When compared to control teleiophiles in
the Tanner V>neutral contrast, pedophiles showed a signicant
deactivation in the right insula. Furthermore, in the between group
contrast of interest (pedophiles>Tanner I, teleiophiles>Tanner
V), there were signicantly greater activation signals seen in the
postcentral gyrus, right middle temporal gyrus, anterior midcingu-
late cortex, and the amygdalae bilaterally (Poeppl etal., 2011). e
authors interpreted these ndings as an easier sexual arousability
in pedophilic as compared to non-paraphilic participants when
stimulated with purposefully non-erotic material (Poeppl etal.,
2011).
In a similar study, Habermeyer etal. (2013a) investigated eight
pedophiles (three with a history of contact oenses, ve with a
history of child pornography consumption) and eight heterosexual
teleiophilic controls in an event-related design consisting of erotic
pictures of boys, girls, men, and women. In an ROI analysis includ-
ing the middle frontal gyrus, only the pedophilic participants
showed activation in the girl contrast, whereas controls showed
deactivation (Habermeyer etal., 2013a). A further nding showed
that during the immediate processing of erotic stimuli, both groups
showed signicant activations in the dorsomedial prefrontal cor-
tex, a nding the authors attributed to the crucial role this region
occupies in the critical evaluation of and attention to sexual stimuli
(Habermeyer etal., 2013a).
Two recent studies investigated functional connectivity in
pedophilia and have supported decreased connectivity associated
with CSA, but not with pedophilia. Specically, Kärgel etal. (2015)
examined functional connectivity at rest (RSFC) in 26 pedophilic
men stratied according to oense status (14 P+CSA, 12 P–CSA)
and 14 HC within (1) the default mode network and (2) the limbic
network. Pedophiles who engaged in CSA depicted diminished
RSFC in both networks compared with HC and P–CSA with
diminished RSFC between the le amygdala and orbitofrontal
as well as anterior prefrontal regions. ese ndings highlight
a diminished resting state functional connectivity in oending
pedophiles as compared to controls, suggesting a relationship
to CSA more than to pedophilia. Using complex multimodal
integration of brain structure and function analyses, Poeppl etal.
(2015) found that the functional role of brain regions that are
altered in pedophilia were linked to non-sexual emotional as well
as neurocognitive and executive functions, which were previously
reported to be impaired in pedophiles. ey suggested that struc-
tural brain alterations aect neural networks for sexual processing
by way of disrupted functional connectivity and that structural
alterations also account for common aective and neurocognitive
impairments in pedophilia.
Further, new methods have been investigating dierences that
go beyond regional activations. Pattern classication is a new
method of analyzing neural activation patterns. e idea of pattern
classication is to use activation patterns in dierent brain regions
in a multivariate approach rather than relying on region by region
comparisons (Linden, 2012). It can be used for classifying groups.
For example, in the eld of sexology pattern classication has been
applied successfully to classify heterosexual and homosexual male
teleiophiles (Ponseti etal., 2009).
Research found that the activations seen in heterosexual and
homosexual pedophiles to child stimuli are nearly indistinguishable
June 2015 | Volume 9 | Article 34414
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
from those in heterosexual and homosexual healthy males to
adult stimuli (Ponseti etal., 2012); this supports the assumption
that pedophilia is primarily a sexual age preference similarly
to teleiophilia. e activation pattern among heterosexual and
homosexual pedophiles and healthy male teleiophiles includes the
caudate nucleus, cingulate cortex, insula, fusiform gyrus, temporal
cortex, occipital cortex, thalamus, amygdala, and cerebellum.
Despite the similarity in activation patterns between pedophilic
and teleiophilic men, the novel pattern classication technique has
been successfully applied based on the presentation of preferred
sexual stimuli and resulted in a mean accuracy of 95%, with 100%
specicity and 88% sensitivity (Ponseti etal., 2012; Mohnke etal.,
2014), thereby showing a promising new approach for classify-
ing subjects. Please refer to Figure3 for a visual explanation of
pattern classication according to Ponseti etal. (2012). ese
studies included fully admitting pedophilic participants only;
therefore, further research should verify its use with partially- or
non-admitting pedophiles. e promise of functional predictors
is, however, also supported by a similar study which, in contrast
to Ponseti etal. (2012), used a highly hypothesis-driven approach
of several impaired functions.
In their study, Walter etal. (2010) could show that a bi-dimen-
sional discriminant function analysis revealed highly signicant
group separation when activations for cognitive appraisal or
passive consumption of visual material are considered in their
respective specic brain regions. A recent study investigated
response inhibition in pedophilic males and found that pedophilic
participants had slower reaction times and less accurate visual
target discrimination which corresponded to greater activation
in the “No-Go” condition for the DLPFC bilaterally, frontal eye
elds, and supplementary motor areas, but in the le anterior cin-
gulate cortex, precuneus, and angular gyrus, they showed greater
activation in the “Go” condition (Habermeyer etal., 2013b) in an
uncorrected voxel-wise analysis.
As research shows, there are regions that dier in neural activa-
tion among heterosexual pedophiles, homosexual pedophiles, and
matched healthy teleiophiles. However, limitations in these early
studies included controlling neither for sexual preference nor
orientation, using insuciently dierentiated inter-study para-
digms such that all generalizations had to be limited to the exact
study and paradigm utilized. Furthermore, pedophilic participants
were all incarcerated or judicially involved [a notable exclusion
to this being (Ponseti etal., 2012)], underscoring the need for
studies investigating non-incarcerated pedophilic participants. As
previous research in normal human sexuality has shown, there are
notable dierences between healthy heterosexual and homosexual
men. is should be kept in mind for future neuroscientic inves-
tigations (Hamann etal., 2004; Ponseti etal., 2006, 2009).
As discussed previously, neuroimaging is a useful way of
investigating the neural correlates of human sexuality in terms of
detecting the arousal pattern associated to the sexual preference
structure. A criticism of previous functional neuroimaging studies
FIGURE 3 | Illustration of pattern classication of pedophiles and healthy controls using individual expression values. Participants with p >0.5
(dark area) were classied as pedophiles. For further details, see Ponseti etal. (2012).
June 2015 | Volume 9 | Article 34415
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
in pedophilia relates to faking. Under the assumption that immedi-
ate processing of sexual stimuli is outside of conscious cognitive
control (bottom-up inuence), results were interpreted so that
(de)-activations were true and not the result of faking (Ponseti
etal., 2009, 2012, 2014). However, studies of test-retest reliabilities
and faking in fMRI research have shown that faking can and does
occur (Lee etal., 2009) and that, ndings are not always reliable
across centers and studies (Maitra etal., 2002; Raemaekers etal.,
2007; Friedman etal., 2008). With the aforementioned limitations
in mind, new research programs will help to dierentiate the true
dierences from methodological artifacts.
The Contribution of Molecular Genetics and
Epigenetics
Even though rst hints for a familial transmission of pedophilia
date back to the early 80s (Ganey etal., 1984), only limited
research has been conducted into the genetic contributions to
pedophilia. Twin studies of sexual orientation hint at a heritable
component of homosexuality (Bailey etal., 2000; Santtila etal.,
2008; Långström et al., 2010). Most recently, a Finnish group
published the rst twin study investigating pedophilia. is was a
population-based twin design analyzing 3967 male twins and their
male siblings. It was shown that genetic inuences contribute to
sexual interest, fantasies, or activity pertaining to children under
the age of 16years (Alanko etal., 2010). However, the heritability
estimated in the study explained only 14.6% of the variance; in
comparison, the heritability of almost all psychiatric disorders
is estimated to be above 30%, with schizophrenia and bipolar
disorder ranging as high as 70–80% (Alanko etal., 2013). Based
on their ndings, the authors concluded that future research
should address the possible interplay of genetic with environ-
mental risk factors, such as own sexual victimization in child-
hood (Bienvenu etal., 2011). Another recently published study
reported genograms of ve families with unusual high occurrence
of paraphilias (mainly pedophilia). ey found familial aggrega-
tion of paraphilias with no clear Mendelian type of transmission.
Intriguingly these families included carriers for dierent types
of possible developmental disorders such as conduct disorders,
deafness, blindness, and epilepsy (Labelle etal., 2012).
No candidate studies nor genome-wide association studies
in the eld of pedophilia have been published today and to our
knowledge, no large-scale eorts to ll this gap are currently under
way. is would also not be feasible considering that the number of
subjects needed in order to expect genome-wide signicant nd-
ings would be in the range of several thousand or ten-thousand.
Given the weak heritability of pedophilia together with the
assumed large eects of early environment and early develop-
ment, and possibly an interaction among these dierent factors,
epigenetics might represent a promising way to disentangle the
biological substrates and possible markers of sexual deviation.
Epigenetics is the study of the dynamic changes in gene regulation,
which the organism achieves using the common mechanisms
of DNA methylation, histone modication, and chromatine
restructuring (Rodenhiser and Mann, 2006). rough epigenetic
mechanisms, the organism can establish a molecular memory of
past gene×environment interactions, with long-lasting eects
on brain circuits and genetic pathways. For example, early life
stress programs the function of the HPA-axis through epigenetic
alterations in the regulation of key genes involved in HPA axis
functioning (Szyf etal., 2005; McGowan etal., 2009; Muragtroyd
etal., 2009). Epigenetic (dys-) regulation plays an important role
in dierent neuropsychiatric disorders and was proven as a suc-
cessful heuristic framework for research in neurodevelopmental
disorders (Krebs etal., 2004; Schroeder etal., 2012). Epigenetic
mechanisms are also involved in the process of tissue dierentia-
tion (Rodenhiser and Mann, 2006) as well as in normal sexual
dimorphic brain development (Nugent etal., 2011). Recent nd-
ings give rise to the view that epigenetic mechanisms are at the
core of sexual dierentiation and serve as the interface between
hormonally transmitted changes and sex chromosome related
eects (Arnold etal., 2012). Its implication in both normal and
abnormal brain development, as well as its role in the etiology
of psychiatric disorders, makes it likely that epigenetic mecha-
nisms widely contribute to the development of the human sexual
preference structure including pedophilia. However, to date, no
investigations of epigenetics in this direction have been published.
Conclusion: What are the Implications and
Future Directions of Neurobiology and
Pedophilia?
Previous research investigated the etiology of pedophilia from
a neurobiological and neurodevelopmental perspective, utiliz-
ing state-of-the-art neuroimaging equipment and methods and
physical markers known to be highly inuenced by developmental
challenges. Although the idea of a neurodevelopmental etiology of
pedophilia has a very wide scope and this idea can be attributed to
other psychological disorders, we feel its relationship to pedophilia
warrants stricter research.
Support for a neurodevelopmental pathway comes from
research investigating epigenetic dysregulation of sexual develop-
ment in general, physical characteristics, and functional as well
as structural brain dierences in pedophilia. Pedophilia seems
to have a small hereditary component, with cases clustering in
families and familial transmission of deviant sexual fantasies and
behaviors (Ganey etal., 1984; Alanko etal., 2010).
Sexually oending and incarcerated pedophilic men show
increased rates of le-handedness, have shorter stature, experi-
ence twice as many head injuries before the age of 13 as normal
counterparts, and seem to have lower intelligence than teleiophilic
men (Blanchard etal., 2003, 2007; Cantor etal., 2004, 2005, 2007).
ese variables are present in pedophilic men signicantly more
oen than in healthy control, but it is not clear if the reason for
this is the sexual behavior disorder, the pedophilic preference, or
even another factor.
e push for neurobiological research has resulted in three
major aforementioned theoretical developments, all attempting
to explain various aspects of pedophilia. e frontal lobe theory
is a contender to explain oenses against children from behavioral
disinhibition and uncontrolled compulsive behaviors. Noticeable
structural and functional dierences in size and function of the
le and right dorsolateral prefrontal and orbitofrontal cortex have
been found in pedophilic men with a history of contact sexual
June 2015 | Volume 9 | Article 34416
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Prenatal
androgen
exposure
•Altered 2D:D4 rao
•Rates of le
handedness ↑
Heritability
Epigenecs
Life events
•Stressful events during
childhood including
child sexual abuse
•Number of head
injuries before age of
13 years ↑
•Lower IQ & shorter
stature
Neuro-
transmier
dysbalance
•Increased
sex drive due
to low serotonergic
inhibion?
•Increased
sex drive due
to high dopaminergic
excitaon?
Funconal
brain
alteraons
•Decreased prefrontal
and temporal
inhibion?
•Alteraon of
neuropychological
funcon
Structural
brain
alteraons
•Volume reducon of
amygdala and
hypothalamus?
Pedophilia
FIGURE 4 | Findings and questions regarding the etiology of pedophilia.
oenses against children (Burns and Swerdlow, 2003; Schier etal.,
2007, 2008a,b; Poeppl etal., 2011).
e temporal-limbic theory tries to explain pedophilia through
structural and functional dierences in the temporal lobes, thus
focusing on the misattributed emotional salience and valence
toward children. Several case studies highlight temporal and
amygdalar lesions or functional activation dierences that might
contribute to the development of a pedophilic sexual preference
(Cohen etal., 2002; Joyal etal., 2007; Schiltz etal., 2007; Walter
etal., 2007; Sartorius etal., 2008).
e dual lobe theory suggests that both frontal and temporal
disturbances are responsible for the range of behaviors seen in
pedophilia, such as diminished impulse control as seen with
orbitofrontal decits and hypersexuality through the temporal
lobes (Seto, 2008, 2009; Poeppl etal., 2013).
erefore, future investigations in the neuroimaging of pedo-
philia should use stricter inclusion/exclusion criteria to better
limit potential confounds and actively recruit non-oending
pedophiles to close the gap in knowledge between oending
and non-oending pedophiles. is will also aid in researchers’
abilities to understand exactly what regions of the brain are
implicated in pedophilic sexual preference development, as
current literature interpretation implicates the brain in an overly
ambitious manner. Examinations of the symptomatology and
clinical aspects of pedophilia should rst try to replicate original
ndings before novel ideas can be properly tested, including
testosterone and its role in pedophilia development or the role
of neurotransmitters such as dopamine and serotonin and their
receptor densities in relation to behavioral perturbations. What
is ultimately needed in this research eld are stricter participant
inclusion criteria and studies utilizing non-oending pedophiles
and non-pedophilic oenders in order to ascertain what dier-
ences are true to pedophilia and those that are true to sexual
oending against children in general. Please refer to Figure4
for a visual of research questions and directions for the etiology
and treatment of pedophilia.
Now that pedophilia is an increasingly accepted research
eld and not only a side issue, scientists are more intensively
investigating not only how it develops, but also how to treat, and
ultimately, how to prevent oending against children. Ultimately,
the success rests with researchers willing to investigate a topic
that still carries a signicant societal stigma load but promises
to oer a signicant improvement not only to patients but also
to society in general.
June 2015 | Volume 9 | Article 34417
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Acknowledgments
We would like the thank Mr. Alexander Pohl and Mr. Sebastian
Mohnke for their insightful comments and expertise during revi-
sion, as well as the reviewers’ comments that helped improve our
manuscript. Support for this manuscript was provided by a grant
from the German Ministry for Education and Research (BMBF)
awarded to JP, MW, KB, BS, and TK (01KR1205A), and a grant
from the German Research Foundation (DFG) awarded to BS and
TK (Schi 1034/3-1). e funding sources played no further role in
the manuscript design or preparation or in the decision to submit
the manuscript for publication.
References
Abel, G. G., Human, J., Warberg, B., and Holland, C. L. (1998). Visual reaction time
and plethysmography as measures of sexual interest in child molesters. Sex. Abuse
10, 81–95.
Abel, G. G., Lawry, S. S., Karlstrom, E. M., Osborn, C. A., and Gillespie, C. F. (1994).
Screening tests for pedophilia. Crim. Justice Behav. 21, 115–131. doi:10.1177/00
93854894021001008
Abracen, J., O’carroll, R., and Ladha, N. (1991). Neuropsychological dysfunction in
sex oenders? J. Forensic Psychiatry 2, 167–177. doi:10.1080/09585189108407646
Ahlers, C. J., Schaefer, G. A., Mundt, I. A., Roll, S., Englert, H., Willich, S. N., etal.
(2011). How unusual are the contents of paraphilias? Paraphilia-associated sexual
arousal patterns in a community-based sample of men. J. Sex. Med. 8, 1362–1370.
doi:10.1111/j.1743-6109.2009.01597.x
Alanko, K., Salo, B., Mokros, A., and Santtila, P. (2013). Evidence for heritability of
adult men’s sexual interest in youth under age 16 from a population-based extended
twin design. J. Sex. Med. 10, 1090–1099. doi:10.1111/jsm.12067
Alanko, K., Santtila, P., Harlaar, N., Witting, K., Varjonen, M., Jern, P., etal. (2010).
Common genetic eects on gender atypical behavior in childhood and sexual
orientation in adulthood: a study of Finnish twins. Arch. Sex. Behav. 39, 81–92.
doi:10.1007/s10508-008-9457-3
Allnutt, S. H., Bradford, J. M. W., Greenberg, D. M., and Curry, S. (1996). Co-morbidity
of alcoholism and the paraphilias. J. Forensic Sci. 41, 234–239.
Arnold, A. P., Chen, X., and Itoh, Y. (2012). “What a dierence an x or y makes: sex
chromosomes, gene dose, and epigenetics in sexual dierentiation,” in Sex and
Gender Dierences in Pharmacology, ed. V. Regitz-Zagrosek (Berlin: Springer),
67–88.
Babchishin, K. M., Karl Hanson, R., and Hermann, C. A. (2011). The char-
acteristics of online sex offenders: a meta-analysis. Sex. Abuse 23, 92–123.
doi:10.1177/1079063210370708
Bailey, J. M., Dunne, M. P., and Martin, N. G. (2000). Genetic and environmental
inuences on sexual orientation and its correlates in an Australian twin sample.
J. Pers. Soc. Psychol. 78, 524–536. doi:10.1037/0022-3514.78.3.524
Bancro, J. H. J., Jones, H. G., and Pullan, B. R. (1966). A simple transducer for
measuring penile erection, with comments on its use in the treatment of sexual
disorders. Behav. Res. er. 4, 239–241. doi:10.1016/0005-7967(66)90075-1
Bao, A.-M., and Swaab, D. F. (2010). Sex dierences in the brain, behavior, and neuro-
psychiatric disorders. Neuroscientist 16, 550–565. doi:10.1177/1073858410377005
Beaton, A. A., Rudling, N., Kissling, C., Taurines, R., and ome, J. (2011). Digit
ratio (2D:4D), salivary testosterone, and handedness. Laterality 16, 136–155.
doi:10.1080/13576500903410369
Beatty, J., and Lucero-Wagoner, B. (2000). “e pupillary system,” in Handbook of
Psychophysiology, 2nd. Edn, eds L. G. Tassinary and G. G. Berntson (New York,
NY: Cambridge University Press), 142–162.
Becerra García, J. A. (2009). Etiology of pedophilia from a neurodevelopmental
perspective: markers and brain alterations. Rev. Psiquiatr. Salud. Ment. 2, 190–196.
doi:10.1016/S1888-9891(09)73237-9
Bechara, A., Damasio, H., and Damasio, A. R. (2000). Emotion, decision
making and the orbitofrontal cortex. Cereb. Cortex 10, 295–307. doi:10.1093/
cercor/10.3.295
Beech, A. R., and Mitchell, I. J. (2005). A neurobiological perspective on attachment
problems in sexual oenders and the role of selective serotonin re-uptake inhibitors
in the treatment of such problems. Clin. Psychol. Rev. 25, 153–182. doi:10.1016/j.
cpr.2004.10.002
Beier, K. M. (1998). Dierential typology and prognosis for dissexual behavior – a
follow-up study of previously expert-appraised child molesters. Int. J. Legal Med.
111, 133–141. doi:10.1007/s004140050133
Beier, K. M., Ahlers, C. J., Goecker, D., Neutze, J., Mundt, I. A., Hupp, E., etal. (2009a).
Can pedophiles be reached for primary prevention of child sexual abuse? First
results of the Berlin prevention project dunkelfeld (PPD). J. Forens. Psychiatry
Psychol. 20, 851–867. doi:10.1080/14789940903174188
Beier, K. M., Neutze, J., Mundt, I. A., Ahlers, C. J., Goecker, D., Konrad, A., etal.
(2009b). Encouraging self-identied pedophiles and hebephiles to seek professional
help: rst results of the prevention project dunkelfeld (PPD). Child Abuse Negl. 33,
545–549. doi:10.1016/j.chiabu.2009.04.002
Beier, K. M., Amelung, T., Kuhle, L., Grundmann, D., Scherner, G., and Neutze, J.
(2013). [Hebephilia as a sexual disorder]. Fortschr. Neurol. Psychiatr. 81, 128–137.
doi:10.1055/s-0032-1330539
Bienvenu, O. J., Davydow, D. S., and Kendler, K. S. (2011). Psychiatric ‘diseases’ versus
behavioral disorders and degree of genetic inuence. Psychol. Med. 41, 33–40.
doi:10.1017/S003329171000084X
Blanchard, R. (2010). e DSM diagnostic criteria for pedophilia. Arch. Sex. Behav.
39, 304–316. doi:10.1007/s10508-009-9536-0
Blanchard, R., Christensen, B. K., Strong, S. M., Cantor, J. M., Kuban, M. E., Klassen, P.,
etal. (2002). Retrospective self-reports of childhood accidents causing uncon-
sciousness in phallometrically diagnosed pedophiles. Arch. Sex. Behav. 31, 511–526.
doi:10.1023/A:1020659331965
Blanchard, R., Klassen, P., Dickey, R., Kuban, M. E., and Blak, T. (2001). Sensitivity and
specicity of the phallometric test for pedophilia in nonadmitting sex oenders.
Psychol. Assess. 13, 118–126. doi:10.1037/1040-3590.13.1.118
Blanchard, R., Kolla, N. J., Cantor, J. M., Klasses, P. E., Dickey, R., Kuban, M. E., etal.
(2007). IQ, handedness, and pedophilia in adult male patients stratied by referral
source. Sex. Abuse 19, 285–309. doi:10.1007/s11194-007-9049-0
Blanchard, R., Kuban, M. E., Klassen, P., Dickey, R., Christensen, B. K., Cantor, J. M.,
etal. (2003). Self-reported head injuries before and aer age 13 in pedophilic and
nonpedophilic men referred for clinical assessment. Arch. Sex. Behav. 32, 573–581.
doi:10.1023/A:1026093612434
Bogaert, A. F. (2001). Handedness, criminality, and sexual oending. Neuropsychologia
39, 465–469. doi:10.1016/S0028-3932(00)00134-2
Bourke, A. B., and Gormley, M. J. (2012). C omparing a pictorial stroop task to viewing time
measures of sexual interest. Sex. Abuse 24, 479–500. doi:10.1177/1079063212438922
Briere, J., and Runtz, M. (1989). University males’ sexual interest in children: predicting
potential indices of “pedophilia” in a nonforensic sample. Child Abuse Negl. 13,
65–75. doi:10.1016/0145-2134(89)90030-6
Briken, P., Hill, A., and Berner, W. (2006). Paraphilien und sexualdelinquenz:
neurobiologische und neuropsychologische aspekte. Z. Sex. Forsch. 19, 295–314.
doi:10.1055/s-2006-955198
Bundeskriminalamt . (2012). Police Crime Statistics Yearbook – 2012, (ed.) P.C. Statistics.
Wiesbaden: Bundeskriminalamt.
Burns, J. M., and Swerdlow, R. H. (2003). Right orbitofrontal tumor with pedophilia
symptom and constructional apraxia sign. Arch. Neurol. 60, 437–440. doi:10.1001/
archneur.60.3.437
Cantor, J. (2012). Is homosexuality a paraphilia? the evidence for and against. Arch.
Sex. Behav. 41, 237–247. doi:10.1007/s10508-012-9900-3
Cantor, J., and Blanchard, R. (2012). White matter volumes in pedophiles, hebephiles,
and teleiophiles. Arch. Sex. Behav. 41, 749–752. doi:10.1007/s10508-012-9954-2
Cantor, J. M., Blanchard, R., Christensen, B. K., Dickey, R., Klassen, P. E., Beckstead,
A. L., etal. (2004). Intelligence, memory, and handedness in pedophilia.
Neuropsychology 18, 3–14. doi:10.1037/0894-4105.18.1.3
Cantor, J. M., Blanchard, R., Robichaud, L. K., and Christensen, B. K. (2005).
Quantitative reanalysis of aggregate data on IQ in sexual oenders. Psychol. Bull.
131, 555–568. doi:10.1037/0033-2909.131.4.555
Cantor, J. M., Kabani, N., Christensen, B. K., Zipursky, R. B., Barbaree, H. E., Dickey, R.,
etal. (2008). Cerebral white matter deciencies in pedophilic men. J. Psychiatr.
Res. 42, 167–183. doi:10.1016/j.jpsychires.2007.10.013
Cantor, J. M., Kuban, M. E., Blak, T., Klassen, P. E., Dickey, R., and Blanchard, R.
(2007). Physical height in pedophilic and hebephilic sexual oenders. Sex. Abuse
19, 395–407. doi:10.1007/s11194-007-9060-5
June 2015 | Volume 9 | Article 34418
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Ó Ciardha, C., and Gormley, M. (2012). Using a pictorial-modied stroop task to
explore the sexual interests of sexual oenders against children. Sex. Abuse 24,
175–197. doi:10.1177/1079063211407079
Cohen, L. J., Nikiforov, K., Gans, S., Poznansky, O., Mcgeoch, P., Weaver, C., etal.
(2002). Heterosexual male perpetrators of childhood sexual abuse: a preliminary
neuropsychiatric model. Psychiatr. Q. 73, 313–336. doi:10.1023/A:1020416101092
Côté, K., Earls, C. M., and Lalumiere, M. L. (2002). Birth order, birth interval,
and deviant sexual preferences among sex offenders. Sex. Abuse 14, 67–81.
doi:10.1177/107906320201400105
Crimes, N. C. F. V. O. (2012). Child, Youth, and Teen Victimization. Washington, DC:
National Center for Victims of Crime. Available at: http://www.victimsofcrime.
org/library/crime-information-and-statistics/child-youth-and-teen-victimization
Dolan, M., Millington, J., and Park, I. (2002). Personality and neuropsychological
function in violent, sexual and arson offenders. Med. Sci. Law 42, 34–43.
doi:10.1177/002580240204200107
Dressing, H., Obergriesser, T., Tost, H., Kaumeier, S., Ruf, M., and Braus, D. F. (2001).
Homosexuelle pädophilie und funkionelle netzwerk – fMRI-fallstudie. Forts chr.
Neurol. Psychiatr. 69, 539–544. doi:10.1055/s-2001-18380
Eastvold, A., Suchy, Y., and Strassberg, D. (2011). Executive function proles of pedo-
philic and nonpedophilic child molesters. J. Int. Neuropsychol. Soc. 17, 295–307.
doi:10.1017/S1355617710001669
Ehrhardt, A. A., and Meyer-Bahlburg, H. F. L. (1979). Prenatal sex hormones and the
developing brain: eects on psychosexual dierentiation and cognitive function.
Annu. Rev. Med. 30, 417–430. doi:10.1146/annurev.me.30.020179.002221
Englert, H., Schaefer, G., Roll, S., Ahlers, C., Beier, K., and Willich, S. (2007). Prevalence
of erectile dysfunction among middle-aged men in a metropolitan area in Germany.
Int. J. Impot. Res. 19, 183–188. doi:10.1038/sj.ijir.3901510
Fagan, P. J., Wise, T. N., Schmidt, C. W. Jr., and Berlin, F. S. (2002). Pedophilia. JAMA
288, 2458–2465. doi:10.1001/jama.288.19.2458
Fang, X., Brown, D. S., Florence, C. S., and Mercy, J. A. (2012). e economic burden
of child maltreatment in the United States and implications for prevention. Child
Abuse Negl. 36, 156–165. doi:10.1016/j.chiabu.2011.10.006
Fazio, R. L., Lykins, A. D., and Cantor, J. M. (2014). Elevated rates of atypical handedness
in paedophilia: theory and implications. Laterality 19, 690–704. doi:10.1080/135
7650X.2014.898648
Fedoro, J. P., and Pinkus, S. (1996). e genesis of pedophilia: testing the ‘abuse to
abuser’ hypothesis. J. Oender Rehabil. 23, 85–101. doi:10.1300/J076v23n03_06
Finkelhor, D., Turner, H., Ormrod, R., and Hamby, S. L. (2009). Violence, abuse,
and crime exposure in a national sample of children and youth. Pediatrics 124,
1411–1423. doi:10.1542/peds.2009-0467
First, M. B. (2011). e inclusion of child pornography in the DSM-5 diagnostic
criteria for pedophilia: conceptual and practical problems. J. Am. Acad. Psychiatry
Law 39, 250–254.
Flor-Henry, P., L ang, R. A., Koles, Z. J., and Frenzel, R. R. (1991). Quantitative EEG studies
of pedophilia. Int. J. Psychophysiol. 10, 253–258. doi:10.1016/0167-8760(91)90036-W
Freund, K. (1963). A laboratory method for diagnosing predominance of homo- or hete-
ro-erotic interest in male. Behav. Res. er. 1, 85–93. doi:10.1016/0005-7967(63)90012-3
Freund, K. (1967). Diagnosing homo- or heterosexuality and erotic age-
preference by means of a psychophysiological test. Behav. Res. er. 5, 209–228.
doi:10.1016/0005-7967(67)90036-8
Freund, K., and Blanchard, R. (1989). Phallometric diagnosis of pedophilia. J. Consult.
Clin. Psychol. 57, 100–105. doi:10.1037/0022-006X.57.1.100
Freund, K., and Kuban, M. (1993). Decient erotic gender dierentiation in pedophilia:
a follow-up. Arch. Sex. Behav. 22, 619–628. doi:10.1007/BF01543304
Freund, K., and Kuban, M. (1994). e basis of the abused abuser theory of pedophilia:
a further elaboration on an earlier study. Arch. Sex. Behav. 23, 553–563. doi:10.1007/
BF01541497
Freund, K., Watson, R., and Dickey, R. (1990). Does sexual abuse in childhood cause
pedophilia: an exploratory study. Arch. Sex. Behav. 19, 557–568. doi:10.1007/
BF01542465
Freund, K., Watson, R., Dickey, R., and Rienzo, D. (1991). Erotic gender dierentiation
in pedophilia. Arch. Sex. Behav. 20, 555. doi:10.1007/BF01550954
Freund, K., and Watson, R. J. (1992). e proportions of heterosexual and homosexual
pedophiles among sex oenders against children: an exploratory study. J. Sex Marital
e r. 18, 34–43. doi:10.1080/00926239208404356
Friedman, L., Stern, H., Brown, G. G., Mathalon, D. H., Turner, J., Glover, G. H., etal.
(2008). Test–retest and between-site reliability in a multicenter fMRI study. Hum.
Brain Mapp. 29, 958–972. doi:10.1002/hbm.20440
Fromberger, P., Jordan, K., Steinkrauss, H., Von Herder, J., Witzel, J., Stolpmann, G.,
etal. (2012a). Diagnostic accuracy of eye movements in assessing pedophilia.
J. Sex. Med. 9, 1868–1882. doi:10.1111/j.1743-6109.2012.02754.x
Fromberger, P., Jordan, K., Von Herder, J., Steinkrauss, H., Nemetschek, R., Stolpmann, G.,
etal. (2012b). Initial orienting towards sexually relevant stimuli: preliminary
evidence from eye movement measures. Arch. Sex. Behav. 41, 919–928. doi:10.1007/
s10508-011-9816-3
Ganey, G. R., Lurie, S. F., and Berlin, F. S. (1984). Is there familial transmission of pedo-
philia? J. Nerv. Ment. Dis. 172, 546–548. doi:10.1097/00005053-198409000-00006
Geer, J. H., Estupinan, L. A., and Manguno-Mire, G. M. (2000). Empathy, social skills,
and other relevant cognitive processes in rapists and child molesters. Aggress. Violent
Behav. 5, 99–126. doi:10.1016/S1359-1789(98)00011-1
George, R. (1930). Human finger types. Anat. Rec. 46, 199–204. doi:10.1002/
ar.1090460210
Georgiadis, J. R., and Kringelbach, M. L. (2012). e human sexual response cycle:
brain imaging evidence linking sex to other pleasures. Prog. Neurobiol. 98, 49–81.
doi:10.1016/j.pneurobio.2012.05.004
Gillespie, N. K., and McKenzie, K. (2000). An examination of the role of neuropsy-
chological decits in mentally disordered sex oenders. J. Sex. Aggress. 5, 21–29.
doi:10.1080/13552600008413293
Graber, B., Hartmann, K., Coman, J. A., Huey, C. J., and Golden, C. J. (1982). Brain
damage among mentally disordered sex oenders. J. Forensic Sci. 27, 125–134.
Green, A. H. (1999). “Female sex oenders,” in Sexual Aggression, ed. J. A. Shaw
(Washington, DC: American Psychiatric Press), 195–210.
Green, R. (2002). Is pedophilia a mental disorder? Arch. Sex. Behav. 31, 467–471.
doi:10.1023/A:1020655231056
Greenberg, D. M., Firestone, P., Nunes, K. L., Bradford, J. M., and Curry, S.
(2005). Biological fathers and stepfathers who molest their daughters:
psychological, phallometric, and criminal features. Sex. Abuse 17, 39–46.
doi:10.1177/107906320501700105
Habermeyer, B., Esposito, F., Händel, N., Lemoine, P., Klarhöfer, M., Mager, R., etal.
(2013a). Immediate processing of erotic stimuli in paedophilia and controls: a case
control study. BMC Psychiatry 13:88. doi:10.1186/1471-244X-13-88
Habermeyer, B., Esposito, F., Handel, N., Lemoine, P., Kuhl, H. C., Klarhofer, M., etal.
(2013b). Response inhibition in pedophilia: an FMRI pilot study. Neuropsychobiology
68, 228–237. doi:10.1159/000355295
Hall, R. C. W., and Hall, R. C. W. (2007). A prole of pedophilia: denition, charac-
teristics of oenders, recidivism, treatment outcomes, and forensic issues. Mayo
Clin. Proc. 82, 457–471. doi:10.4065/82.4.457
Hamann, S., Herman, R. A., Nolan, C. L., and Wallen, K. (2004). Men and women
dier in amygdala response to visual sexual stimuli. Nat. Neurosci. 7, 411–416.
doi:10.1038/nn1208
Harris, G. T., Rice, M. E., Quinsey, V. L., and Chaplin, T. C. (1996). Viewing time as a
measure of sexual interest among child molesters and normal heterosexual men.
Behav. Res. er. 34, 389–394. doi:10.1016/0005-7967(95)00070-4
Hucker, S., Langevin, R., Wortzman, G., Bain, J., Handy, L., Chambers, J., etal. (1986).
Neuropsychological impairment in pedophiles. Can. J. Behav. Sci. 18, 440–448.
doi:10.1111/j.1743-6109.2009.01564.x
Hughes, J. R. (2007). Review of medical reports on pedophilia. Clin. Pediatr. 46,
667–682. doi:10.1177/0009922807301483
Jespersen, A. F., Lalumiere, M. L., and Seto, M. C. (2009a). Sexual abuse history among
adult sex oenders and non-sex oenders: a meta-analysis. Child Abuse Negl. 33,
179–192. doi:10.1016/j.chiabu.2008.07.004
Jespersen, A. F., Lalumière, M. L., and Seto, M. C. (2009b). Sexual abuse history among
adult sex oenders and non-sex oenders: a meta-analysis. Child Abuse Negl. 33,
179–192. doi:10.1016/j.chiabu.2008.07.004
Jordan, K., Fromberger, P., Stolpmann, G., and Müller, J. L. (2011a). e role of testos-
terone in sexuality and paraphilia – a neurobiological approach. Part I: testosterone
and sexuality. J. Sex. Med. 8, 2993–3007. doi:10.1111/j.1743-6109.2011.02394.x
Jordan, K., Fromberger, P., Stolpmann, G., and Müller, J. L. (2011b). e role of testos-
terone in sexuality and paraphilia – a neurobiological approach. Part II: testosterone
and paraphilia. J. Sex. Med. 8, 3008–3029. doi:10.1111/j.1743-6109.2011.02394.x
Joyal, C. C., Black, D. N., and Dassylva, B. (2007). e neuropsychology and neurology
of sexual deviance: a review and pilot study. Sex. Abuse 19, 155–173. doi:10.1007/
s11194-007-9045-4
Kalichman, S. (1991). Psychopathology and personality characteristics of criminal
sexual offenders as a function of victim age. Arch. Sex. Behav. 20, 187–197.
doi:10.1007/BF01541943
June 2015 | Volume 9 | Article 34419
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Kärgel, C., Massau, C., Weiss, S., Walter, M., Kruger, T. H., and Schier, B. (2015).
Diminished functional connectivity on the road to child sexual abuse in pedophilia.
J. Sex. Med. 12, 783–795. doi:10.1111/jsm.12819
Klucken, T., Schweckendiek, J., Merz, C. J., Tabbert, K., Walter, B., Kagerer, S.,
etal. (2009). Neural activations of the acquisition of conditioned sexual
arousal: eects of contingency awareness and sex. J. Sex. Med. 6, 3071–3085.
doi:10.1111/j.1743-6109.2009.01405.x
Kramer, R. (2011). APA guidelines ignored in development of diagnostic criteria for
pedohebephilia. Arch. Sex. Behav. 40, 233–235. doi:10.1007/s10508-010-9683-3
Krebs, M. R. H., Morozova-Roche, L. A., Daniel, K., Robinson, C. V., and Dobson,
C. M. (2004). Observation of sequence specicity in the seeding of protein amyloid
brils. Protein Sci. 13, 1933–1938. doi:10.1110/ps.04707004
Kruger, T. H. C., and Schier, B. (2011). Neurocognitive and personality factors in
homo- and heterosexual pedophiles and controls. J. Sex. Med. 8, 1650–1659.
doi:10.1111/j.1743-6109.2009.01564.x
Kuban, M., Barbaree, H. E., and Blanchard, R. (1999). A comparison of volume and
circumference phallometry: response magnitude and method agreement. Arch.
Sex. Behav. 28, 345–359. doi:10.1023/A:1018700813140
Labelle, A., Bourget, D., Bradford, J. M. W., Alda, M., and Tessier, P. (2012). Familial
paraphilia: an pilot study with the construction of genograms. ISRN Psychiatry
2012, 1–10. doi:10.5402/2012/692813
Lalumière, M. L., Harris, G. T., Q uinsey, V. L., and Rice, M. E. (1998). Sexual deviance
and number of older brothers among sexual oenders. Sex. Abuse 10, 5–15.
Langevin, R., Wortzman, G., Dickey, R., Wright, P., and Handy, L. (1988).
Neuropsychological impairment in incest oenders. Ann. Sex Res. 1, 401–415.
doi:10.1177/107906328800100304
Långström, N., Rahman, Q., Carlström, E., and Lichtenstein, P. (2010). Genetic and
environmental eects on same-sex sexual behavior: a population study of twins in
Sweden. Arch. Sex. Behav. 9, 75–80. doi:10.1007/s10508-008-9386-1
Laws, D. R., and Marshall, W. L. (1990). “A conditioning theory of the etiology and
maintenance of deviant sexual preference and behavior,” in Handbook of Sexual
Assault: Issues, eories, and Treatment of the Oender, eds W. L. Marshall, D. R.
Laws , and H. E. Barbaree (New York, NY: Plenum Press), 209–230.
Lee, T. M. C., Au, R. K. C., Liu, H.-L., Ting, K. H., Huang, C.-M., and Chan, C.
C. H. (2009). Are errors dierentiable from deceptive responses when feigning
memory impairment? An fMRI study. Brain Cogn. 69, 406–412. doi:10.1016/j.
bandc.2008.09.002
Lenz, B., Müller, C. P., Stoessel, C., Sperling, W., Biermann, T., Hillemacher, T.,
etal. (2012). Sex hormone activity in alcohol addiction: integrating organi-
zational and activational eects. Prog. Neurobiol. 96, 136–163. doi:10.1016/j.
pneurobio.2011.11.001
Letourneau, E. J. (2002). A comparison of objective measures of sexual arousal and
interest: visual reaction time and penile plethysmography. Sex. Abuse 14, 203–219.
doi:10.1023/A:1015366324325
Linden, D. E. J. (2012). e challenges and promise of neuroimaging in psychiatry.
Neuron 73, 8–22. doi:10.1016/j.neuron.2011.12.014
Maitra, R., Roys, S. R., and Gullapalli, R. P. (2002). Test-retest reliability estimation
of functional MRI data. Magn. Reson. Med. 48, 62–70. doi:10.1002/mrm.10191
Manning, J. T., Churchill, A. J., and Peters, M. (2007). e eects of sex, ethnicity,
and sexual orientation on self-measured digit ratio (2D:4D). Arch. Sex. Behav. 36,
223–233. doi:10.1007/s10508-007-9171-6
Marshall, W. A., and Tanner, J. M. (1969). Variations in pattern of pubertal changes in
girls. Arch. Dis. Child. 44, 291–303. doi:10.1136/adc.44.235.291
Marshall, W. A., and Tanner, J. M. (1970). Variations in the pattern of pubertal changes
in boys. Arch. Dis. Child. 45, 13–23. doi:10.1136/adc.45.239.13
McGowan, P. O., Sasaki, A., D’ Alessio, A. C., Dymov, S., Labonté, B., Szyf, M., etal.
(2009). Epigenetic regulation of the glucocorticoid receptor in the human brain
associates with childhood abuse. Nat. Neurosci. 12, 342–348. doi:10.1038/nn.2270
Mendez, M. F., Chow, T., Ringman, J., Twitchell, G., and Hinkin, C. H. (2000).
Pedophilia and temporal lobe disturbances. J. Neuropsychiatry Clin. Neurosci. 12,
71–76. doi:10.1176/jnp.12.1.71
Mohnke, S., Muller, S., Amelung, T., Kruger, T. H., Ponseti, J., Schier, B., etal. (2014).
Brain alterations in paedophilia: a critical review. Prog. Neurobiol. 122C, 1–23.
doi:10.1016/j.pneurobio.2014.07.005
Mokros, A., Gebhard, M., Heinz, V., Marschall, R. W., Nitschke, J., Glasgow, D. V.,
etal. (2012a). Computerized assessment of pedophilic sexual interest through
self-report and viewing time: reliability, validity, and classication accuracy of the
anity program. Sex. Abuse 25, 230–258. doi:10.1177/1079063212454550
Mokros, A., Osterheider, M., and Nitschke, J. (2012b). Pädophilie: prävelenz, ätiologie
und diagnostik. Nervenarzt 83, 355–358. doi:10.1007/s00115-011-3322-7
Muragtroyd, C., Patchev, A. V., Wu, Y., Micale, V., Bockmühl, Y., Fischer, D., etal.
(2009). Dynamic DNA methylation programs persist adverse eects of early-life
stress. Nat. Neurosci. 12, 1559–1566. doi:10.1038/nn.2436
Neutze, J., Grundmann, D., Scherner, G., and Beier, K. M. (2012). Undetected and
detected child sexual abuse and child pornography oenders. Int. J. Law Psychiatry
35, 168–175. doi:10.1016/j.ijlp.2012.02.004
Neutze, J., Seto, M. C., Schaefer, G. A., Mundt, I. A., and Beier, K. M. (2011). Predictors
of child pornography oenses and child sexual abuse in a community sample of
pedophiles and hebephiles. Sex. Abuse 23, 212–242. doi:10.1177/1079063210382043
Nugent, B. M., Schwarz, J. M., and Mccarthy, M. M. (2011). Hormonally mediated
epigenetic changes to steroid receptors in the developing brain: implications for
sexual dierentiation. Horm. Behav. 59, 338–344. doi:10.1016/j.yhbeh.2010.08.009
O’Doherty, J., Critchley, H., Deichmann, R., and Dolan, R. J. (2003). Dissociating
valence of outcome from behavioral control in human orbital and ventral prefrontal
cortices. J. Neurosci. 23, 7931–7939.
Phoenix, C. H., Goy, R. W., Gerall, A. A., and Young, W. C. (1959). Organizing action
of prenatally administered testosterone propionate on the tissues mediating
mating behavior in the female guinea pig. Endocrinology 65, 369–382. doi:10.1210/
endo-65-3-369
Poeppl, T. B., Eickho, S. B., Fox, P. T., Laird, A. R., Rupprecht, R., Langguth, B.,
etal. (2015). Connectivity and functional proling of abnormal brain structures
in pedophilia. Hum. Brain Mapp. 36, 2374–2386. doi:10.1002/hbm.22777
Poeppl, T. B., Langguth, B., Laird, A. R., and Eickho, S. B. (2014). e functional
neuroanatomy of male psychosexual and physiosexual arousal: a quantitative
meta-analysis. Hum. Brain Mapp. 35, 1404–1421. doi:10.1002/hbm.22262
Poeppl, T. B., Nitschke, J., Dombert, B., Santtila, P., Greenlee, M. W., Osterheider, M.,
etal. (2011). Functional cortical and subcortical abnormalities in pedophilia:
a combined study using a choice reaction time task and fMRI. J. Sex. Med. 8,
1660–1674. doi:10.1111/j.1743-6109.2011.02248.x
Poeppl, T. B., Nitschke, J., Santtila, P., Schecklmann, M., Langguth, B., Greenlee, M. W.,
etal. (2013). Association between brain structure and phenotypic characteristics
in pedophilia. J. Psychiatr. Res. 47, 678–685. doi:10.1016/j.jpsychires.2013.01.003
Ponseti, J., Bosinski, H. A., Wol, S., Peller, M., Jansen, O., Mehdorn, H. M., etal.
(2006). A functional endophenotype for sexual orientation in humans. Neuroimage
33, 825–833. doi:10.1016/j.neuroimage.2006.08.002
Ponseti, J., Granert, O., Jansen, O., Wol, S., Beier, K., Neutze, J., etal. (2012).
Assessment of pedophilia using hemodynamic brain response to sexual stimuli.
Arch. Gen. Psychiatry 69, 187–194. doi:10.1001/archgenpsychiatry.2011.130
Ponseti, J., Granert, O., Jansen, O., Wol, S., Mehdorn, H., Bosinkski, H., etal. (2009).
Assessment of sexual orientation using the hemodynamic brain response to visual
sexual stimuli. J. Sex. Med. 6, 1628–1634. doi:10.1111/j.1743-6109.2009.01233.x
Ponseti, J., Granert, O., Van Eimeren, T., Jansen, O., Wol, S., Beier, K., etal. (2014).
Human face processing is tuned to sexual age preferences. Biol. Lett. 10, 20140200.
doi:10.1098/rsbl.2014.0200
Quinsey, V. L., Ketsetzis, M., Earls, C., and Karamonoukian, A. (1996). Viewing
time as a measure of sexual interest. Ethol. Sociobiol. 17, 341–354. doi:10.1016/
S0162-3095(96)00060-X
Raemaekers, M., Vink, M., Zandbelt, B., Van Wezel, R. J. A., Kahn, R. S., and Ramsey,
N. F. (2007). Test–retest reliability of fMRI activation during prosaccades and
antisaccades. Neuroimage 36, 532–542. doi:10.1016/j.neuroimage.2007.03.061
Rahman, Q. (2005). Fluctuating asymmetry, second to fourth nger length ratios and
human sexual orientation. Psychoneuroendocrinology 30, 382–391. doi:10.1016/j.
psyneuen.2004.10.006
Rahman, Q., and Symeonides, D. J. (2008). Neurodevelopmental correlates of
paraphilic sexual interests in men. Arch. Sex. Behav. 37, 166–172. doi:10.1007/
s10508-007-9255-3
Rahman, Q., and Wilson, G. D. (2003). Sexual orientation and the 2nd to 4th
nger length ratio: evidence for organising eects of sex hormones or devel-
opmental instability? Psychoneuroendocrinology 28, 288–303. doi:10.1016/
S0306-4530(02)00022-7
Rice, M. E., and Harris, G. T. (2002). Men who molest their sexually immature
daughters: is a special explanation required? J. Abnorm. Psychol. 111, 329–339.
doi:10.1037/0021-843X.111.2.329
Rieger, G., and Savin-Williams, R. C. (2012). e eyes have it: sex and sexual orientation
dierences in pupil dilation patterns. PLoS ONE 7:e40256. doi:10.1371/journal.
pone.0040256
June 2015 | Volume 9 | Article 34420
Tenbergen et al. The neurobiology of pedophilia
Frontiers in Human Neuroscience | www.frontiersin.org
Rodenhiser, D., and Mann, M. (2006). Epigenetics and human disease: translating basic
biology into clinical applications. Can. Med. Assoc. J. 174, 341–348. doi:10.1503/
cmaj.050774
Safron, A., Barch, B., Bailey, J. M., Gitelman, D. R ., Parrish, T. B., and Reber, P. J. (2007).
Neural correlates of sexual arousal in homosexual and heterosexual men. Behav.
Neurosci. 121, 237–248. doi:10.1037/0735-7044.121.2.237
Santtila, P., Sandnabba, N. K., Harlaar, N., Varjonen, M., Alanko, K., and von Der
Pahlen, B. (2008). Potential for homosexual response is prevalent and genetic. Biol.
Psychol. 77, 102–105. doi:10.1016/j.biopsycho.2007.08.006
Sartorius, A., Ruf, M., Kief, C., Demirakca, T., Bailer, J., Ende, G., etal. (2008). Abnormal
amygdala activation prole in pedophilia. Eur. Arch. Psychiatry Clin. Neurosci. 258,
271–277. doi:10.1007/s00406-008-0782-2
Schäfer, G. A., Engert, H. S., Ahlers, C. J., Roll, S., Willich, S. N., and Beier,
K. M. (2003). Erektionsstörung und lebensqualität – erste ergebnisse der berliner
männer-studie. Sexuologie 10, 50–60.
Schaefer, G. A., Mundt, I. A., Feelgood, S., Hupp, E., Neutze, J., Ahlers, C. J., etal. (2010).
Potential and dunkelfeld oenders: two neglected target groups for prevention of
child sexual abuse. Int. J. Law Psychiatry 33, 154–163. doi:10.1016/j.ijlp.2010.03.005
Schier, B., Krueger, T., Paul, T., De Grei, A., Forsting, M., Leygraf, N., etal. (2008a).
Brain response to visual sexual stimuli in homosexual pedophiles. J. Psychiatry
Neurosci. 33, 23–33.
Schier, B., Paul, T., Gizewski, E., Forsting, M., Leygraf, N., Schedlowski, M., etal.
(2008b). Functional brain correlates of heterosexual paedophilia. Neuroimage 41,
80–91. doi:10.1016/j.neuroimage.2008.02.008
Schier, B., Peschel, T., Paul, T., Gizewski, E., Forsting, M., Leygraf, N., etal. (2007).
Structural brain abnormalities in the frontostriatal system and cerebellum in
pedophilia. J. Psychiatr. Res. 41, 753–762. doi:10.1016/j.jpsychires.2006.06.003
Schiffer, B., and Vonlaufen, C. (2011). Executive dysfunctions in pedo-
philic and nonpedophilic child molesters. J. Sex. Med. 8, 1975–1984.
doi:10.1111/j.1743-6109.2010.02140.x
Schiltz, K., Witzel, J., Northo, G., Zierhut, K., Gubka, U., Fellmann, H., etal. (2007).
Brain pathology in pedophilic oenders. Arch. Gen. Psychiatry 64, 737–746.
doi:10.1001/archpsyc.64.6.737
Schroeder, J. W., Smith, A. K., Brennan, P. A., Conneely, K. N., Kilaru, V., Knight, B. T.,
etal. (2012). DNA methylation in neonates born to women receiving psychiatric
care. Epigenetics 7, 409–414. doi:10.4161/epi.19551
Schulz, K. M., Molenda-Figueira, H. A., and Sisk, C. L. (2009). Back to the future: the
organizational-activational hypothesis adapted to puberty and adolescence. Horm.
Behav. 55, 597–604. doi:10.1016/j.yhbeh.2009.03.010
Sellbom, M., and Verona, E. (2007). Neuropsychological correlates of psychopathic
traits in a non-incarcerated sample. J. Res. Pers. 41, 276–294. doi:10.1016/j.
jrp.2006.04.001
Seto, M. C. (2008). Pedophilia and Sexual Oending Against Children: eory, Assessment,
and Intervention. Washington, DC: American Psychological Association.
Seto, M. C. (2009). Pedophilia. Annu. Rev. Clin. Psychol. 5, 391–407. doi:10.1146/
annurev.clinpsy.032408.153618
Seto, M. C. (2010). Child pornography use and internet solicitation in the diagnosis of
pedophilia. Arch. Sex. Behav. 39, 591–593. doi:10.1007/s10508-010-9603-6
Seto, M. C., Cantor, J. M., and Blanchard, R. (2006). Child pornography oenses
are a valid diagnostic indicator of pedophilia. J. Abnorm. Psychol. 115, 610–615.
doi:10.1037/0021-843X.115.3.610
Seto, M. C., Karl Hanson, R., and Babchishin, K. M. (2011). Contact sexual
offending by men with online sexual offenses. Sex. Abuse 23, 124–145.
doi:10.1177/1079063210369013
Seto, M. C., Lalumiere, M. L., and Kuban, M. (1999). e sexual preferences of incest
oenders. J. Abnorm. Psychol. 108, 267–272. doi:10.1037/0021-843X.108.2.267
Seto, M. C., Wood, J. M., Babchishin, K. M., and Flynn, S. (2012). Online solicitation
oenders are dierent from child pornography oenders and lower risk contact
sexual oenders. Law Hum. Behav. 36, 320–330. doi:10.1037/h0093925
Stoléru, S., Fonteille, V., Cornélis, C., Joyal, C., and Moulier, V. (2012). Functional
neuroimaging studies of sexual arousal and orgasm in healthy men and women: a
review and meta-analysis. Neurosci. Biobehav. Rev. 36, 1481–1509. doi:10.1016/j.
neubiorev.2012.03.006
Suchy, Y., Eastvold, A. D., Strassberg, D. S., and Franchow, E. I. (2014). Understanding
processing speed weaknesses among pedophilic child molesters: response style vs.
neuropathology. J. Abnorm. Psychol. 123, 273–285. doi:10.1037/a0035812
Suchy, Y., Whittaker, J. W., Strassberg, D. S., and Eastvold, A. (2009). Neurocognitive dif-
ferences between pedophilic and nonpedophilic child molesters. J. Int. Neuropsychol.
Soc. 15, 248–257. doi:10.1017/S1355617709090353
Szyf, M., Weaver, I. C., Champagne, F. A., Dorio, J., and Meaney, M. J. (2005).
Maternal programming of steroid receptor expression and phenotype through
DNA methylation in the rat. Front. Neuroendocrinol. 26:139–162. doi:10.1016/j.
yfrne.2005.10.002
Tarter, R. E., Hegedus, A. M., Alterman, A. I., and Katz-Garris, L. (1983). Cognitive
capacities of juvenile violent, nonviolent, and sexual oenders. J. Nerv. Ment. Dis.
171, 564–567. doi:10.1097/00005053-198309000-00007
Voracek, M., Manning, J. T., and Dressler, S. G. (2007). Repeatability and interobserver
error of digit ratio (2D:4D) measurements made by experts. Am. J. Hum. Biol. 19,
142–146. doi:10.1002/ajhb.20581
Wakeeld, J. C. (2012). e DSM-5’s proposed new categories of sexual disorder:
the problem of false positives in sexual diagnosis. Clin. Soc. Work J. 40, 213–223.
doi:10.1007/s10615-011-0353-2
Walter, M., Ponseti, J., Witzel, J., and Bogerts, B. (2010). Neurobiological markers for
the diagnosis and treatment of pedophiliacs and their role in prevention of sexual
abuse of children. Forensic Psychiatry Psychother. 17, 115–136.
Walter, M., Witzel, J., Wiebking, C., Gubka, U., Rotte, M., Schiltz, K., etal. (2007).
Pedophilia is linked to reduced activation in hypothalamus and lateral prefrontal
cortex during visual erotic stimulation. Biol. Psychiatry 62, 698–701. doi:10.1016/j.
biopsych.2006.10.018
Wijlman, M., Bijleveld, C., and Hendriks, J. (2010). Women don’t do such things!
Characteristics of female sex oenders and oender types. Sex Abuse 22, 135–156.
doi:10.1177/1079063210363826
Williams, T. J., Pepitone, M. E., Christensen, S. E., Cooke, B. M., Huberman, A. D.,
Breedlove, N. J., etal. (2000). Finger-length ratios and sexual orientation. Nature
404, 455–456. doi:10.1038/35006555
Wood, R. I., and Newman, S. W. (1999). Androgen receptor immunoreactivity in the
male and female Syrian hamster brain. J. Neurobiol. 39, 359–370. doi:10.1002/
(SICI)1097-4695(19990605)39:3<359::AID-NEU3>3.0.CO;2-W
Wright, S. (2010). Depathologizing consensual sexual sadism, sexual masochism,
transvestic fetishism, and fetishism. Arch. Sex. Behav. 39, 1229–1230. doi:10.1007/
s10508-010-9651-y
Wright, S. (2014). Kinky parents and child custody: the eect of the dsm-5 dier-
entiation between the paraphilias and paraphilic disorders. Arch. Sex. Behav. 43,
1257–1258. doi:10.1007/s10508-013-0250-6
Zhong, J., Riin-Graboi, A., Ta, A. T., Yap, K. L., Chuang, K. H., Meaney, M. J., etal.
(2013). Functional networks in parallel with cortical development associate with
executive functions in children. Cereb. Cortex 24, 1937–1947. doi:10.1093/cercor/
bht051
Conict of Interest Statement: e authors declare that the research was conducted
in the absence of any commercial or nancial relationships that could be construed
as a potential conict of interest. e Reviewer Stuart Brody declares that, despite
having collaborated with the author Tillmann H. C. Kruger, the review process was
handled objectively.
Copyright © 2015 Tenbergen, Wittfoth, Frieling, Ponseti, Walter, Walter, Beier, Schier
and Kruger. is is an open-access article distributed under the terms of the Creative
Commons Attribution License (CC BY). e use, distribution or reproduction in other
forums is permitted, provided the original author(s) or licensor are credited and that
the original publication in this journal is cited, in accordance with accepted academic
practice. No use, distribution or reproduction is permitted which does not comply with
these terms.
