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The Psychobiology of Authentic and Simulated
Dissociative Personality States
The Full Monty
Antje A.T.S. Reinders, PhD,*†Antoon T.M. Willemsen, PhD,‡Eline M. Vissia, MSc,†
Herry P.J. Vos, MD,§ Johan A. den Boer, MD, PhD,‡and Ellert R.S. Nijenhuis, PhD||
Abstract: The etiology of dissociative identity disorder (DID) remains a topic
of debate. Proponents of the fantasy model and the trauma model of DID have
both called for more empirical research. To this end, the current study presents
new and extended data analyses of a previously published H
2
15
O positron emis-
sion tomography imaging study. This study included 29 subjects: 11 patients
with DID and 10 high- and 8 low-fantasy-prone DID-simulating mentally healthy
control subjects. All subjects underwent an autobiographical memory script–driven
(neutral and trauma related) imagery paradigm in 2 (simulated) dissociative
personality states (neutral and trauma related). Psychobiological and psycho-
physiological data were obtained. Results of the new post-hoc tests on the psy-
chophysiological responses support the trauma model. New results of the brain
imaging data did not support the fantasy model. This study extends previ-
ously published results by offering important new supporting data for the trauma
model of DID.
Key Words: Dissociative identity disorder, fantasy model, fantasy proneness,
neuroimaging, trauma model
(JNervMentDis2016;00: 00–00)
Despite its inclusion in the latest version of the Diagnostic Manual
of Mental Disorders (DSM-5; APA, 2013) and a comprehensive
review (Dalenberg et al., 2012), the validity of dissociative identity dis-
order (DID) continues to be disputed (Dalenberg et al., 2014; Lynn et al.,
2014). The current Journal has relatively recently been a platform of de-
bate between proponents of the fantasy model and trauma model regard-
ing 2 original publications (Boysen and VanBergen, 2013a; Paris, 2012),
which were extensively commented on (Brand et al., 2013a, 2013b;
Boysen and VanBergen, 2013b; Dell, 2013; Martínez-Taboas et al.,
2013; McHugh, 2013; Paris, 2013; Ross, 2013; and Sar et al., 2013).
Only 1 neurobiological study (by the current authors, Reinders
et al., 2012) has tested the position that DID is related to fantasy prone-
ness (Gleaves, 1996; Lilienfeld et al., 1999; Lynn et al., 2012, 2014) by
including DID patients and both high- and low-fantasy-prone DID-
simulating healthy control subjects. The focus of that study was to test
whether fantasy proneness could explain the brain imaging results from
a within-patient study (Reinders et al., 2006). Recently supported and ex-
tended by other neuroimaging studies in DID patients (Chalavi et al.,
2015a, 2015b; Schlumpf et al., 2013, 2014), the findings were at odds
with the claim that the complex phenomenology and psychobiology of
DID are due to fantasy proneness, suggestion, and motivated role playing.
The type and number of statistical tests in Reinders et al. (2012) were lim-
ited to the study’s hypotheses, and important additional analyses remained
unexplored or unreported. The current article reports the Full Monty by
presenting results of new additional exploratory data analyses.
Types of Personality States
According to the DSM-5, DID is characterized by, among others,
the presence of 2 or more distinct dissociative “personality states.”This
terminology is different from previous DSM versions where the term
identity states was used. In line with the latter terminology, we previ-
ously have used the term dissociative identity states, and different pro-
totypes of dissociative identity states were indicated as neutral identity
states and trauma-related identity states (Reinders et al., 2006, 2012,
2014; Reinders and Willemsen, 2014). However, our f irst publication
used the terminology neutral personality state (NPS) and trauma-
related personality state (TPS) (Reinders et al., 2003), which is in line
with the current DSM-5 terminology and will be used again in the re-
mainder of this article. These various indicators were derived from the
terms apparently normal part of the personality and emotional part of
the personality, respectively, which are formulated in the theory of
structural dissociation of the personality (Nijenhuis et al., 2002a; Van
der Hart et al., 2006) and used in recent publications (Schlumpf et al.,
2013, 2014). This theory defines dissociation as a division of personal-
ity into different types of subsystems, each with their own first-person
perspective, that is, their own point of view as to who they are, what
the world is like, and how they relate to that world (Nijenhuis and
Van der Hart, 2011; Nijenhuis, 2015).
As NPS, DID patients concentrate on functioning in daily life,
commonly try to hide their pathology, and avoid traumatic memories
when they can. As a result, NPS has not or not sufficiently integrated
these memories (Reinders et al., 2003). In contrast, TPS does have con-
scious access to these memories, recalls them as personal experiences,
and is bodily and emotionally affected by them. As TPS, the patients are
fixated in traumatic memories and engage in defensive actions such as
freeze and flight, when they feel threatened (Nijenhuis et al., 2004),
thereby activating fast subcortical response routes in the brain (LeDoux,
2000; Reinders et al., 2006). Patients, as TPS, can either engage in active
kinds of physical defense (e.g., freeze, flight, fight), indicating dominance
of the sympathetic nervous system, or they can engage in death feigning
primarily mediated by the dorsal vagal branch of the parasympathetic
nervous system (Nijenhuis and Den Boer, 2009). Of note, alternative
models exist, such as the orbitofrontal hypothesis by Forrest (2001).
This is a neurodevelopmental model underlining deficient function-
ality of the orbitofrontal region in the brain. Within this model, the
orbitofrontal lobe is hypothesized to be affected by early trauma
(Dorahy et al., 2014). This model is in line with work from Schore
(2003) and is furthermore supported by 2 controlled brain imaging
studies that found bilateral frontal perfusion differences between DID
patients and control subjects (Sar et al., 2001, 2007).
*Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuro-
science, King’s College London, London, United Kingdom; Departments of
†Neuroscience and ‡Nuclear Medicine and Molecular Imaging, University
of Groningen, University Medical Center Groningen; §Outpatient Department
Addiction Clinic, Groningen, the Netherlands; and ‖Clienia Littenheid, Psychia-
trische Klinik, Littenheid, Switzerland.
Send reprint requests to Antje A.T.S. Reinders, PhD, Department of Psychosis
Studies, Institute of Psychiatry, Psychology and Neuroscience, King’sCollege
London, De Crespigny Park, PO 40, London SE5 8AF, United Kingdom.
E-mail: a.a.t.s.reinders@gmail.com; a.a.t.s.reinders@kcl.ac.uk.
Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.
ISSN: 0022-3018/16/ 0000–0000
DOI: 10.1097/NMD.0000000000000522
ORIGINAL ARTICLE
The Journal of Nervous and Mental Disease •Volume 00, Number 00, Month 2016 www.jonmd.com 1
Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
Review of Perfusion and Functional Magnetic
Resonance Imaging Studies in DID
Imaging neuroscience has been around for more than 20 years
and is by now the predominant technique in behavior and cognitive neu-
roscience (Friston, 2009). However, very few neuroimaging studies have
been conducted in patients with DID (Dalenberg et al., 2012; Dorahy
et al., 2014; Reinders, 2008, Reinders and Willemsen, 2014).
Resting State Studies: The first functional brain imaging study in
a single patient with DID was a positron emission tomography (PET)
scan of the resting brain state (Mathew et al., 1985). The study included
3 mentally healthy control subjects and revealed hyperperfusion in the
right temporal cortex of the DID patient. Four studies applied the
low-spatial-resolution imaging technique single-photon emission com-
puted tomography, of which 2 were uncontrolled case studies (Saxe
et al., 1992; Sheehan et al., 2006). These case studies also found the in-
volvement of the temporal lobe of the brain in DID. Sar et al. (2001,
2007) included the largest sample of 21 DID patients in studies into
DID using brain imaging techniques to date. These 2 studies consis-
tently found bilateral orbitofrontal hypoperfusion differences between
patients and control subjects.
Using arterial spin labeling perfusion magnetic resonance imag-
ing (MRI), 2 major prototypes of dissociative parts, that is, an NPS and
a hyperaroused TPS, were examined (Schlumpf et al., 2014). Compared
with TPS, NPS showed elevated perfusion in bilateral thalamus. Com-
pared with NPS, TPS had increased perfusion in the dorsomedial pre-
frontal cortex, primary somatosensory cortex, and motor-related areas.
Perfusion patterns for simulated NPS and TPS were different. Fitting
their reported role-play strategies, the actors activated brain structures
involved in visual mental imagery and empathizing feelings.
Vo l u n t a r y “Switching”Studies: Two uncontrolled functional MRI
(fMRI) case studies examined brain activation patterns associated with
voluntary switching between different dissociative personality states
(Savoy et al., 2012; Tsai et al., 1999). Savoy et al. (2012) found involve-
ment of the dorsolateral prefrontalcortex, the anterior prefrontal cortex,
and orbitofrontal cortex, as well as bilateralactivation in the nucleus ac-
cumbens, an area in the ventral striatum. Tsai et al. (1999) did not find
involvement of the prefrontal cortical areas associated with voluntary
switching, but observed brain activity in hippocampal areas, as well
as the parahippocampus, medial temporal structures, substantia nigra,
and the global pallidus, which is a part of the dorsal striatum (Tsai
et al., 1999). On the other hand, Sar et al. (2001) found that bilateral
orbitofrontal hypoperfusion during resting state is independent of per-
sonality state. This finding suggests that orbitofrontal hypoperfusion
is a biomarker for DID.
Task-Related Brain Activation Studies: Using f MRI, a relatively
high temporal and spatial resolution brain imaging technique, brain ac-
tivation of 16 dissociative disorder patients and 16 mentally healthy
control subjects was studied during a working-memory task (Elzinga
et al., 2007). Dissociative disorder patients outperformed control sub-
jects despite feeling more fearful and less concentrated while activating
the left anterior prefrontal cortex, left dorsolateral prefrontal cortex, and
the left parietal cortex more than control subjects. The prefrontal activa-
tion, but not the parietal activation, was independent of task difficulty.
During an fMRI, task neutral and angry faces were subliminally
presented to 11 individuals with DID and 15 DID-simulating mentally
healthy actors, and reaction times and changes in brain activation were
investigated (Schlumpf et al., 2013). Abnormal reaction times were
found for TPS, but not for NPS, and TPS activated different brain areas
including the parahippocampal gyrus, the brainstem, face-sensitive re-
gions, and motor-related areas. The actors activated different neural pat-
terns as compared with patients.
A multisubject PET study reported that neutral identity states
and trauma-related identity states are associated with different brain
activation patterns when confronted with trauma-related cues (Reinders
et al., 2003, 2006). They reported the involvement of mainly the cortical
multimodal posterior association areas, the subcortical amygdala, and
subparts of the dorsal striatum (i.e., the caudate and putamen) in the psy-
chopathology of DID. These findings were not linked to fantasy proneness
(Reinders et al., 2012). Neither high- nor low-fantasy-prone mentally
healthy women instructed and motivated to simulate the involved disso-
ciative personality states enacted the psychophysiological and neural
activation patterns of the authentic dissociative personality states.
In summary, functional differences in DID have been reported
throughout the brain dependent on a variety of tasks: in the temporal
(Mathew et al., 1985; Sar et al., 2001; Saxe et al., 1992; Sheehan
et al., 2006; Tsai et al., 1999), frontal (Elzinga et al., 2007; Sar et al.,
2001, 2007; Savoy et al., 2012) and occipital (Sar et al., 2007) cortices,
the amygdala and dorsal striatum (Reinders et al., 2006, 2012), nu-
cleus accumbens (Savoy et al., 2012), and hippocampal and pallidum
structures (Tsai et al., 1999; Schlumpf et al., 2014). Hence, a conver-
gence of findings to disseminate neurobiological markers for the psy-
chopathology of DID is still needed.
A Neurobiological Model for DID: Recently, a neurobiological
model for DID has been formulated (Reinders et al., 2014) combining
neuroimaging research on the dissociative subtype of posttraumatic
stress disorder (Lanius et al., 2010) and DID. This model proposes that
the NPS in DID activates prefrontal and cingulate areas as well as the
posterior association areas and parahippocampal gyri when confronted
with trauma-related information. The prefrontal and cingulate are core
in the overmodulation of emotion (Lanius et al., 2010), whereas the
posterior association areas and (para)hippocampal regions are thought
to be involved in the suppression of unwanted autobiographical memo-
ries (Anderson et al., 2004). It further proposes that the TPS in DID ac-
tivates the insula and amygdala, as well as the dorsal striatum, while
reacting to trauma-related stimuli/material. The insula and amygdala
are activated during undermodulation of emotion (Lanius et al., 2010),
whereas the dorsal striatum has beenproposed toplay an important role
in the switching between identity states (Tsai et al., 1999), as well as in
maintaining state stability of a dissociative identity state (Reinders
et al., 2006; Reinders et al., 2012; Schlumpf et al., 2013).
Trauma and Fantasy Models of DID
Supporters of the opposed trauma and fantasy models (Dalenberg
et al., 2012) of DID are engaged in a debate regarding the validity of DID
as a mental disorder and its causes (i.e., traumatization or fantasy prone-
ness, suggestibility, suggestion, and simulation) (Bremner, 2010; Coons,
2005; Fraser, 2005; Giesbrecht et al., 2008, 2010; Gleaves, 1996; Piper
and Merskey, 2004a, 2004b; Sar, 2005; Spanos, 1994). The fantasy
model of DID entails the idea that this disorder can be easily and readily
created in motivated suggestible individuals and that few suggestions
suffice to generate the symptoms of DID (Spanos, 1994). This model
(Giesbrecht et al., 2008; Merckelbach and Muris, 2001; Merckelbach
et al., 2002; Piper and Merskey, 2004a, 2004b; Pope et al., 2006) is also
referred to as the sociocognitive model of DID (Lilienfeld et al., 1999;
Spanos, 1994) or non–trauma-related model (Reinders et al., 2012) and
involves the idea that DID is a simulation caused by high suggestibility
and/or fantasy proneness (Giesbrecht and Merckelbach, 2006; Giesbrecht
et al., 2007; Merckelbach et al., 2000; Merckelbach and Van de Ven,
2001), suggestive psychotherapy, and other suggestive sociocultural
influences (e.g., the media and/or the church; Lilienfeld et al., 1999;
Spanos, 1994). Although fantasy proneness and suggestibility refer to
different concepts, they are highly correlated (Braffman and Kirsch,
1999; Levin and Spei, 2004; Merckelbach and Van de Ven, 2001). Of
note, people who argue againstthe DID trauma model do not solely talk
about fantasy proneness, but also suggest the possibility of mild cogni-
tive impairment (Giesbrecht et al., 2008) or sleep deprivation (Van
Heugten–Van der Kloet et al., 2014) as an alternative explanation. To
date, proponents of the fantasy model of DID have not studied individ-
uals with DID using brain imaging techniques.
Reinders et al. The Journal of Nervous and Mental Disease •Volume 00, Number 00, Month 2016
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The trauma model (Dalenberg et al., 2012; Reinders et al., 2012)
entails that DID is related to a combination of factors that include
chronic emotional neglect, as well as emotional, physical, and/or sex-
ual abuse from early childhood, insufficient integrative capacity, at-
tachment disorder, and lack of affect regulation by caretakers (Dell
and O’Neil, 2010; Gleaves, 1996; Spiegel, 2006; Van der Hart et al.,
2006). In this view, DID is thought to be at the far end of the spectrum
of trauma-related psychiatric disorders (Chalavi et al., 2015a, 2015b).
Proponents of the trauma model acknowledge that some features of
dissociative personality states can be influenced by sociocultural fac-
tors, that false-positive cases of DID have evolved in a treatment set-
ting, and that some psychiatric patients imitate DID (Draijer and Boon,
1999). They also note that there are differences between authentic and
imitated DID (Draijer and Boon, 1999) and that there is no evidence that
DID can (sub-)consciously be created by sociocultural factors (Gleaves,
1996). Furthermore, even if DID symptoms can be created iatrogenically
or can be enacted, this does not mean that genuine trauma-related DID
does not exist (Elzinga et al., 1998).
The Full Monty
The current study presents new and extended data analyses on
the basis of previously published data (Reinders et al., 2012), which in-
cludes within-NPS and between-personality state (TPS vs. NPS) com-
parisons and conjunction analyses. Brain activation patterns of DID
patients and high- and low-fantasy-prone DID-simulating control sub-
jects are compared. On the basis of the trauma model’spredictions
and the newly delineated neurobiological models of dissociation (Lanius
et al., 2010; Reinders et al., 2014), we hypothesize (i) more brain activa-
tion in the prefrontal regions and the anterior cingulate in response to
the trauma-related text as compared with neutral text for NPS to estab-
lish overmodulation of emotions, (ii) activation in the dorsal striatum
for maintaining state stability of a dissociative personality state (Reinders
et al., 2014) for the comparison of NPS and TPS reactivity to the neutral
text, (iii) differences between high-fantasy-prone (CH) and low-fantasy-
prone (CL) DID-simulating subjects not involving brain regions from
the neurobiological models of dissociation, and (iv) no or little overlap
between brain activation patterns for DID and CH and/or CL for the
conjunction analyses (Friston et al., 1999; Price and Friston, 1997).
Finally, authors of a relatively recent article reviewing simulation
protocols in studies involving subjects with (simulated) DID remarked
that for the psychophysiological data in Reinders et al. (2012) “the au-
thors do not report specif ic post hoc test results”(Boysen and VanBergen,
2014) (p. 52). In reply to this, we also report the results of these specific
post hoc tests on the psychophysiological data.
In summary, the current study aims to inform on the neurobiol-
ogy of DID concerning the differential processing of trauma and neutral
text within the NPS, the differential processing of the neutral text be-
tween NPS and TPS, and concerning overlap in brain activation be-
tween DID patients and DID-simulating control subjects.
METHODS
Participants
Twenty-nine subjects participated in the PET study, which was
approved by the Medical Ethical Committee of the University Medical
Center Groningen: 11 patients with DID, 10 high-fantasy-prone DID-
simulating mentally healthy control subjects (CH), and 8 low-fantasy-
prone DID-simulating mentally healthy control subjects (CL). Control
subjects were carefully matched for sex (all female) and age. Differences
in age were not significant (DID vs. CH: F
1,18
=0,499,p=0.489,not
statistically signif icant; and DID vs. CL: F
1,16
= 0.153; p=0.701,not
statistically significant). A detailed description of the mentally healthy
control subjects included in this study and the DID enactment proce-
dure can be found in a previous publication (Reinders et al., 2012;
Reinders and Willemsen, 2014). In short, the control subjects were re-
cruited by local newspaper advertisements, did not report potentially
traumatizing events such as physical abuse and emotional neglect,
and completed the Traumatic Experience Checklist (TEC; Nijenhuis
et al., 2002b), Somatoform Dissociation Questionnaire (SDQ-20;
Nijenhuis et al., 1996), and the Creative Experiences Questionnaire
(CEQ) (Merckelbach et al., 2001), which measures fantasy proneness.
A CEQ cutoff forhigh fantasy proneness of 10 was used, which the de-
velopers of the CEQ recommended for the current sample (personal
communication by e-mail). This resulted in 2 groups of control subjects:
a high-fantasy-prone group and a low-fantasy-prone group (Table 1). The
control subjects received written and oral information on NPS and TPS
and were instructed to simulate these different dissociative personality
states. Control subjects were asked to provide their most painful memory
to serve as an analog for the patients’personal trauma memories, as well
as a neutral personal episodic memory. They were subsequently instructed
how to write the autobiographical analog “neutral”and “trauma”memory
scripts (MSs). For the experiment, they had to train themselves inbeing
an NPS who is unresponsive or underresponsive to the painful experi-
ence, and in being a TPS, a dissociative personality state in which they
are stuck in and tend to recurrently re-experience the painful memory.
A detailed description of the DID patients can be found else-
where (Reinders et al., 2003, 2006). In short, 11 patients (all female)
participated (i) whose treatment had progressed to include therapeutic
exposure to trauma-related memories, (ii) who met criteria for DID, as
operationalized in the Structured Clinical Interview for DSM-IV Disso-
ciative Disorders (Steinberg, 1993), (iii) who had at least 1 TPS and 1
NPS that they could activate on demand in an experimental setting,
and (iv) whose selected TPS had displayed signs of sympathetic ner-
vous system dominance under perceived threat in clinical situations.
H.P.J.V. or the patient’s therapist structurally evaluated if the intended
NPS or TPS had been present during the experimental condition. This
was done by debrief ing the presence of the dissociative personality
state under investigation and by checking potential interference among
personality states during the execution of the experimental tasks.
Image Acquisition and Data Processing
Cerebral blood flow PET (Siemens/CTI ECAT HR+, Knoxville,
TN) data and autonomic (systolic and diastolic blood pressure, dis-
crete heart rate, and heart rate variability [HRV]) and subjective (control
subjects’subjective sensorimotor and emotional experiences) reac-
tions were obtained (see, for details, Statistical Analyses and Results;
Reinders et al., 2003, 2006, 2012) (main paper and supplementary ma-
terials, S2). Dissociative identity disorder patients, as well as high- and
low-fantasy-prone control subjects, were examined in the 2 different
types of personality states during an MS-driven imagery paradigm.
Four conditions were obtained in a repeated-measures design: NPSn
TABLE 1. Age and Clinical Measures for the Control Subjects
Mean (SD)
CH (n = 10) CL (n = 8)
Age
a
38.2 (10.9) 42.5 (10.1)
CEQ 13.7 (3.2) 3.9 (1.6)
TEC 0.7 (1.3) 0.4 (0.5)
SDQ-20 22 (2.4) 20.9 (1.5)
Mean and SD for the high-fantasy-prone group and low-fantasy-prone group
of the following questionnaires: TEC (Nijenhuis et al., 2002b), SDQ-20
(Nijenhuis et al., 1996), and CEQ (Merckelbach et al., 2001), which measures
fantasy proneness.
a
Age of DID patients: 41.0 (6.1).
The Journal of Nervous and Mental Disease •Volume 00, Number 00, Month 2016 Psychobiology of DID: Full Monty
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(NPS exposed to the neutral MS), NPSt (NPS exposed to the trauma-
related MS), TPSn (TPS exposed to the neutral MS), and TPSt (TPS
exposed to the trauma-related MS), where the last minor character
(n or t) denotes the content of the MS (neutral or trauma related). Data
acquisition, reconstruction, attenuation correction, spatial transforma-
tion, and spatial smoothing (isotropic Gaussian kernel of 12 mm) were
performed as usual (Reinders et al., 2012).
Data Analyses
The brain imaging data of the 3 groups were preprocessed and
statistically analyzed in SPM5 (www.fil.ion.ucl.ac.uk/spm) in a 3
22 factorial design, which allows for the assessment of within- and
between-personality state effects within and between the 3 groups. The
subjective reactions and the autonomic reactions were included as
group-specific covariates in thegeneral linear model (3-factor main ef-
fects [subject, condition, and group], 4 conditions, and the group
condition interaction) of SPM5 after principal component analysis
(Reinders et al., 2003, 2006, 2012). Global cerebral blood flow was in-
cluded as a nuisance covariate (analysis of covariance by subject).
Comparisons of interest included within-personality state ef-
fects and between-personality state effects. Within-personality state
effects refer to different patterns of brain activity associated with re-
actions to the trauma-related and neutral text within the trauma-
related or NPS in DID, CH, and CL (e.g., DID [TPSt-TPSn]–CL
TABLE 2. Neurobiological Results: MS Effects Within Dissociative Personality State
L/R Brain Region BA
Between Group
DID-CH DID-CL CH-CL
xyzT
a
kE x y z T
a
kE x y z T
a
kE
TPSt-TPSn
Cortical areas NS
L Insula BA 13 −38 −14 14 3.61 48 −38 −14 14 4.61 327
R Postcentral gyrus BA 43 68 −14 18 3.58 19
R I. temporal gyrus BA 20 32 −12 −44 3.57 9
Subcortical areas NS
LAmygdala −12 −4−26 4.05 132
L Caudate nucleus (dorsal part) −12 4 16 4.13 39
R Caudate nucleus (dorsal part) 24 2 14 3.64 53 26 2 20 3.76 56
L Caudate nucleus (tail) −22 −24 16 3.60 13
Cerebellum NS NS NS
TPSn-TPSt
Cortical areas NS
R Cingulate sulcus BA 6/24 20 −10 52 3.76 101
L (Pre)cuneus BA 7/31/18/19 −12 −66 26 4.25 210 −16 68 28 4.26 181
R Fusiform gyrus BA 19/37 34 58 −20 4.11 478
L S. occipital gyrus/angular gyrus BA 19/39 −42 80 28 3.59 29
R Occipitotemporal sulcus BA 20/37 48 −38 −12 3.65 23 46 −36 −14 4.31 89
R Intra-Parietal sulcus BA 7/40 34 −36 36 3.72 62 34 −34 38 4.13 122
R S. parietal lobule/precuneus BA 7 28 −66 32 3.49 34
R M. Temporal gyrus BA 21 60 2 −16 3.33 11
Cerebellum NS NS
L Cerebellum (anterior lobe) −4−44 −14 3.62 48
NPSt-NPSn
Cortical areas NS NS
L S. frontal gyrus BA 9 −16 56 34 3.80 100
R S. frontal gyrus BA 9 32 56 34 3.53 40
Subcortical areas NS NS NS
Cerebellum NS NS NS
NPSn-NPSt
Cortical areas NS NS
R Hippocampus 34 −30 −10 4.78 335
Subcortical areas NS NS NS
Cerebellum NS NS NS
Overview of brain areas with statistically significant cerebralblood flow changes when comparing DID patients to high or low DID-simulating control subjects (CH
and CL, respectively) and high- to low-fantasy-prone control subjects (CH vs. CL) for the trauma-related MS effects within neutral or trauma-related dissociative per-
sonality states. Results for TPS are shown at the top and NPS at the bottom. Results for the TPSt-TPSn and vice versa have been published previously (Reinders et al.,
2012) and are shown here for convenience as the conjunction analyses in Table 5 are dependent on these comparisons.
a
p< 0.05, corrected for multiple comparisons.
I indicates inferior; L/R, left/right; M, middle; S, superior.
Reinders et al. The Journal of Nervous and Mental Disease •Volume 00, Number 00, Month 2016
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TABLE 3. Psychophysiogical Results: MS Effects Within Dissociative Personality State
Trauma-Related Personality State: Differential Processing
of the Trauma-Related and Neutral Text
Neutral Personality State: Differential Processing of
the Trauma-Related and Neutral Text
DID (TPSt-TPSn) >
CH (TPSt-TPSn)
DID (TPSt-TPSn) >
CL (TPSt-TPSn)
CH (TPSt-TPSn) >
CL (TPSt-TPSn)
DID (NPSt-NPSn) >
CH (NPSt-NPSn)
DID (NPSt-NPSn) >
CL (NPSt-NPSn)
CH (NPSt-NPSn) >
CL (NPSt-NPSn)
Subjective ratings
Sensory rating F
1,20
= 33.71, p<0.001
a
F
1,18
= 27.15, p<0.001
a
NS NS NS NS
DID (mean, 4.39; SD, 2.04) DID (mean, 4.39; SD, 2.04) CH (mean, 0.51; SD, 0.57) DID (mean, 0.60; SD, 1.24) DID (mean, 0.60; SD, 1.24) CH (mean, −0.10; SD, 0.28)
CH (mean, 0.51; SD, 0.57) CL (mean, 0.46; SD, 0.69) CL (mean, 0.46; SD, 0.69) CH (mean, −0.10; SD, 0.28) CL (mean, −0.03; SD, 0.16) CL (mean, −0.03; SD, 0.16)
Emotional rating F
1,20
= 16.24, p=0.001
a
F
1,18
= 23.97, p<0.001
a
NS NS NS NS
DID(mean,5.42;SD,1.88) DID(mean,5.42;SD,1.88) CH(mean,2.21;SD,1.76) DID(mean,1.32;SD,1.74) DID(mean,1.32;SD,1.74) CH(mean,0.59;SD,1.43)
CH(mean,2.21;SD,1.76) CL(mean,1.63;SD,1.30) CL(mean,1.63;SD,1.30) CH(mean,0.59;SD,1.43) CL(mean,0.29;SD,0.47) CL(mean,0.29;SD,0.47)
Autonomic reactions
Heart rate
frequency
F
1,20
= 24.42, p<0.001
a
F
1,18
= 18.53, p<0.001
a
NS NS^ NS^ NS
DID (mean, 11.45; SD, 7.00) DID (mean, 11.45; SD, 7.00) CH (mean, 0.20; SD, 1.72) DID (mean, 3.00; SD, 3.46) DID (mean, 3.00; SD, 3.46) CH (mean, −0.88; SD, 5.20)
CH (mean, 0.20; SD, 1.72) CL (mean, 0.46; SD, 1.84) CL (mean, 0.46; SD, 1.84) CH (mean, −0.88; SD, 5.20) CL (mean, 0.38; SD, 1.27) CL (mean, 0.38; SD, 1.27)
Systolic blood
pressure
F
1,20
= 11.37, p=0.003
a
F
1,18
=5.53,p= 0.031* F
1,17
= 7.04, p=0.017* NS NS NS
DID (mean, 12.95; SD, 12.46) DID (mean, 12.95; SD, 12.46) CH (mean, −0.47; SD, 1.66) DID (mean, 4.50; SD, 7.16) DID (mean, 4.50; SD, 7.16) CH (mean, 0.30; SD, 2.92)
CH (mean, −0.47; SD, 1.66) CL (mean, 2.33; SD, 2.79) CL (mean, 2.33; SD, 2.79) CH (mean, 0.30; SD, 2.92) CL (mean, −0.25; SD, 3.90) CL (mean, −0.25; SD, 3.90)
Diastolic blood
pressure
F
1,20
= 12.95, p=0.002
a
F
1,18
=8.49,p= 0.010* NS NS^ NS^ NS
DID (mean, 7.36; SD, 5.37) DID (mean, 7.36; SD, 5.37) CH (mean, −0.20; SD, 4.11) DID (mean, 4.91; SD, 7.15) DID (mean, 4.91; SD, 7.15) CH (mean, 0.45; SD, 3.59)
CH (mean, −0.20; SD, 4.11) CL (mean, 1.71; SD, 1.11) CL (mean, 1.71; SD, 1.11) CH (mean, 0.45; SD, 3.59) CL (mean, −0.38; SD, 2.11) CL (mean, −0.38; SD, 2.11)
HRV average F
1,19
= 11.06, p=0.004
a
F
1,17
=8.58,p= 0.010* NS NS NS NS
DID (mean, −107.94; SD, 95.30) DID (mean, −107.94; SD, 95.30) CH (mean, −0.62; SD, 15.84) DID (mean, −24.48; SD, 54.63) DID (mean, −24.48; SD, 54.63) CH (mean, 5.64; SD, 17.36)
CH (mean, −0.62; SD, 15.84) CL (mean, −0.78; SD, 11.32) CL (mean, −0.78; SD, 11.32) CH (mean, 5.64; SD, 17.36) CL (mean, −5.62; SD, 14.87) CL (mean, −5.62; SD, 14.87)
This table shows the results for the post hoc tests between the 3 groups for the within dissociative personality state processing of the trauma-related text as compared with the processing of the neutral text. As
hypotheses were 1 sided, only 1 directional test was performed and reported here.
a
Corrected for multiple comparisons.
*p< 0.05 uncorrected for multiple comparisons.
NS indicates not statistically significant; NS^, trend: 0.05 < p< 0.10 uncorrected.
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[TPSt-TPSn]). Between-personality state effects refer to different pat-
terns of brain activity associated with reactions to the trauma-related
text and the neutral text, respectively, between different types of person-
ality states in DID, CH, and CL (e.g., DID [TPSt-NPSt]–CH [TPSt-
NPSt]). Conjunction analyses (Friston et al., 1999; Price and Friston,
1997) were conducted on both the between- and within-personality
state effects between DID and CH, DID and CL, and DID, CH, and CL.
Conjunction analyses test for conjoint activation patterns be-
tween conditions and/or groups, therewith allowing for the assessment
of overlap in brain activation between patients and control subjects. The
current study comprises 3 between-group comparisons, namely, DID
versus CH, DID versus CL, and CH versus CL. Hence, conjoint brain
activation between DID and CH, DID and CL, and DID and CL and
CH can be investigated. Some overlap of brain activity between groups
is expected because experimental settings were very similar. To investi-
gate whether conjoint activation between the DID group and the control
subject groups exists, statistical parametric maps were thresholded at a
whole-brain corrected threshold of p< 0.05. The statistical parametric
maps obtained from the comparisons between DID and control subjects
were thresholded using an uncorrected threshold of p< 0.001 (Reinders
et al., 2006) and explored for a priori hypothesized brain areas.
Multiple-comparisons correction was performed, usingfalse discovery
rate statistics (Genovese et al., 2002), for whole brain and for the a
priori regions of interest (ROIs). In the latter case, a small volume cor-
rection was applied using a sphere with radius of 9 mm (Reinders et al.,
2005). A priori hypothesized ROIs were areas reported in Reinders
et al. (2006) (note that most of these are also reported in Reinders
et al. (2012) in the “Within group: DID only”columns) and areas in-
cluded in the neurobiological model for DID (Reinders et al., 2014),
independent of lateralization (hence both hemispheres were explored).
Activation localization was performed as usual (Reinders et al., 2012).
Only clusters larger than 8 voxels are reported, taking into account the spa-
tial resolution of the PET camera. Only the first peak voxel of a cluster is
reported (note that this differs from Reinders et al., 2012, where multiple
peak voxels of a cluster were investigated). Brain regions and Brodmann
areas (BAs) were defined using both the Talairach atlas (Talairach and
Tournoux, 1988) and Deamon (Lancaster et al., 2000). Activations in
sulci were defined using Brain Tutor (www.brainvoyager.com).
For the psychophysiological data, the F and pvalues are reported,
as well as the mean and SD. Bonferroni correction was applied to correct
for the number of tests per psychophysiological measure. Values with a
p< 0.0042 were reported as significant after the correction for multiple
comparisons; results uncorrected for multiple comparisons are reported
with p< 0.05, and trends are reported for values 0.05 < p< 0.10 uncor-
rected for multiple comparisons.
RESULTS
Within-Personality State Effects
Different neural reactivity to the neutral and trauma-related text
within both TPS (top part) and NPS (bottom part) is listed in Table 2.
Results of the psychophysiological measures are listed in Table 3.
In contrast to the high-fantasy-prone control subjects, the NPS
of DID activated the bilateral superior frontal gyrus while listening to
the trauma-related text as compared with listening to the neutral text
(Fig. 1A). Comparing listening to the trauma-related text and listening
to the neutral text, there were trends for NPS of DID to have higher
heart rate and more diastolic blood pressure than either CH or CL. These
comparisons did not yield differences between these groups for HRV
or systolic blood pressure.
When comparing the NPSof CH with the NPS of CL, only right
hippocampus deactivation was found for CH while listening to the
trauma -related text as compared with listening to the neutral text (Fig. 1B).
None of these groups’psychophysiological reactions were significantly
different for this comparison.
Between-Personality State Effects
Differences in neural responses in relation to text effects between
TPS and NPS are givenin Table 4 (trauma-related text effects at the top,
neutral text effects at the bottom). Results of the psychophysiological
measures are listed in Table 5.
Dissociative identity disorder as compared with CH and DID
as compared with CL activated the left and bilateral caudate nucleus,
respectively, in response to the neutral text in the TPS versus NPS
(Fig. 1C). None of the post hoc tests on the psychophysiological mea-
sures reached significance.
The left amygdala and cerebellum were activated when compar-
ing the processing of the trauma-related text in TPS versus NPS in CH
to the CL group, which were also found when comparing the DID to the
CH group. Of the psychophysiological measures, only the systolic blood
pressure was found to be significantly higher in the CH as compared
with the CL group when processing the trauma-related text in the TPS.
Conjunction Analyses
The conjunction analyses are presented in Table 6. There was no
significant overlap found in brain activation patterns between the DID
FIGURE 1. “Glass brain”renderings of significant effects. A and B show differences in the processing of the trauma-related text (indicated with “t”)
and the neutral text (indicated with “n”) within the NPS. For statistical values and coordinates, see Table 1. A shows brain activation in the bilateral
(B.) superior (S.) frontal gyrus for the DID group as compared with the high-fantasy-prone mentally healthy DID-simulating control subjects
(p< 0.001, uncorrected for multiple comparisons, clusters larger than 8 voxels are depicted). B shows a deactivation in the right (R.) hippocampus for
high-fantasy-prone mentally healthy DID-simulating control subjects as compared with low-fantasy-prone mentally healthy DID-simulating control
subjects (p< 0.001 uncorrected for multiple comparisons, clusters larger than 8 voxels are depicted). C shows differential processing of the neutral text
(indicated with “n”) between the NPS and TPS. For statistical values and coordinates, see Table 3. C shows brain activation in the bilateral (B.) caudate
nucleus for the DID group as compared with the low-fantasy-prone mentally healthy DID-simulating control subjects (p< 0.001, uncorrected for
multiple comparisons, clusters larger than 8 voxels are depicted).
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TABLE 4. Neurobiological Results: MS Effects Between Dissociative Personality States
Between Group
DID-CH DID-CL CH-CL
L/R Brain Region BA x y z T*kE x y z T*kE x y z T*kE
TPSt-NPSt
Cortical areas NS
R Postcentral gyrus BA 43 68 −14 14 3.44 12 68 −14 18 4.45** 106
R Precentral gyrus BA 6 66 8 20 3.87 41
R Insula BA 13 46 −12 26 3.41 16
Subcortical areas
LAmygdala −6−6−26 3.75 129 −16 −2−20 3.51 43
L Caudate nucleus
(dorsal part)/insula
_/BA 13 −12 2 18 3.90 34 −12 4 164.71**568
R Caudate nucleus (dorsal
part)/Putamen
24 −2 144.38352 26 0 185.09**490
L Putamen −24 −18 14 3.55 29
R Parietal operculum BA 40/43 48 −2223.40 37
Cerebellum NS
L Cerebellum
(dorsal-medial part)
−6−46 −34 3.63 47 −8−36 −10 3.54 38
NPSt-TPSt
Cortical areas NS
R Cingulate gyrus BA 32 8 14 36 3.74 89
L Cuneus/precuneus BA 7/18/19/31 −8−66 26 4.72 921 −12 −72 30 3.64 92
BA 18/19 −16 −90 36 3.56 20
RCuneus BA18/19 12−80 22 3.86 252
L S. frontal sulcus BA 6 −34 −2523.64 36
R S. frontal
sulcus/cingulate sulcus
BA 4/6 28 −16 44 3.61 33 20 −10 46 3.53 72
RFusiform
gyrus/lingual gyrus
BA 18 26 −96 −20 3.34 34
L Lingual gyrus BA 18 −4−90 −10 4.33** 616
L S. occipital
gyrus/angular gyrus
BA 19/39 −38 −82 30 3.72 82 −42 −78 32 4.27** 128
R Occipitotemporal sulcus BA 20/37 48 −40 −12 4.53 92 46 −36 −14 5.24** 294
L Parahippocampal gyrus BA 35 −40 −46 −43.75 18−40 −46 −6 4.73** 780
R Parahippocampal gyrus BA 36 20 −52 2 3.46 52 22 −52 0 4.26** 482
L Intraparietal sulcus BA 7/40 −34 −50 34 4.36 117
R Intraparietal sulcus BA 7/40 30 −38 40 4.36 249 34 −34 38 3.52 30
RS.parietal
lobule/precuneus
BA 7 24 −64 30 3.95 108 24 −64 36 3.80** 48
X Rectal gyrus BA 11 0 28 −12 3.82** 85
L M. temporal gyrus BA 21 −54 −24 −10 3.71** 63
R M. temporal gyrus BA 21 62 −6−14 3.64 15 62 −6−14 4.16** 120
Subcortical areas NS NS NS
Cerebellum NS NS NS
TPSn-NPSn
Cortical areas NS NS NS
Subcortical areas NS
L Caudate nucleus
(dorsal part)
−18 −6183.6528−20 −2183.86 65
R Caudate nucleus
(dorsal part)
30 −6184.02 225
Cerebellum NS NS NS
(Continued on next page)
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group and CH for both the within- and between-personality state com-
parisons. When adding the CL group, we found conjoint activation in
the 3 groups in the right primary auditory cortex, the right frontal, and bi-
lateral temporal regions for the within-NPS comparison only. No conjoint
(de)activation was found for the within-TPS comparisons or the between-
personality states comparisons.
Conjoint deactivation for processing of the trauma-related text
between the DID group and CL group was found for the within-NPS
comparison in the bilateral temporal gyrus and the right occipitotemporal
gyrus. No conjoint (de)activation was found for the within-TPS com-
parisons. Conjoint activation for the between-personality state com-
parisons of the processing of the trauma-related text was found in
the left orbitofrontal, temporal gyrus, amygdala and cerebellum, and
right occipitotemporal gyrus. A conjoint deactivation was found in
the right precentral gyrus.
DISCUSSION
Proponents of the trauma and fantasy models of DID have called
for more neurobiological data on this disorder. Conducted in this light,
the present study provides extended results from our PET study involv-
ing patients with DID and DID-simulating high- and low-fantasy-prone
mentally healthy control subjects (Reinders et al., 2012; Reinders and
Willemsen, 2014). New results were found, such as bilateral activation
of the superior frontal gyrus within the NPS of the DID patients in re-
sponse to the trauma-related text as compared with the high-fantasy-
prone control subjects, caudate nucleus activation in the TPS as com-
pared with NPS when processing the neutral text in DID patients as
compared with high- or low-fantasy-prone control subjects, and hippo-
campal activation differences between the DID-simulating high- and
low-fantasy-prone mentally healthy control groups. The results of the
new conjunction analyses confirm our previous findings that DID is
not due to high levels of fantasy proneness. Furthermore, in response
to requests by Boysen and VanBergen (2014, p. 52), we performed
post hoc tests of the original psychophysiological data and found that
for most measures the DID patients have significantly higher scores
as compared with high- or low-fantasy-prone DID-simulating mentally
healthy control subjects. Neither high- nor low-fantasy-prone DID-
simulating mentally healthy control subjects were able to simulate this
psychophysiological hyperarousal, which is inconsistent with the fan-
tasy model of DID. The inability of simulators to imitate DID on phys-
iological measures, regardless of the level of suggestibility, refutes the
Fantasy Model’s propositions.
Our most important finding is consistent with our neurobiologi-
cal model that NPS engages prefrontal regions when listening to the
trauma-related text as compared with listening to the neutral text. New re-
search concerning trauma and dissociation (Lanius et al., 2010, 2012;
Reinders et al., 2014) allowed us to perform an ROI analysis, which re-
vealed bilateral activation of the superior frontal gyrus in the comparison
of DID patients to high-fantasy-prone control subjects (CH). This activa-
tion is hypothesized in the neurobiological model for dissociative post-
traumatic stress disorder (Lanius et al., 2010) and DID (Reinders et al.,
2014). Hyperactivation of the superior frontal gyrus suppresses the sym-
pathetic nervous system, which in turn leads to hyporesponsiveness of
the psychophysiological system. This is evidenced by the lack of signif-
icant results in the psychophysiological data (Table 3). Interestingly, the
activation of the superior frontal gyrus only differs between DID and
CH, and therefore, this area seems to be similarly activated for DID
and low-fantasy-prone control subjects (CL). For this finding, we have
3 possible explanations: (1) we included more high CH than CL sub-
jects, so that the absence of a significantly different effect might be
due to limited statistical power. This idea is supported by a recent study
(Reinders et al., 2014), which compared the DID patients with a large
set of control subjects (fantasy prone independent) and which reported
bilateral superior, middle, and medial frontal gyrus activations. It seems
that more statistical power confirms the involvement of the frontal brain
regions in dissociation; (2) a trait characteristic of subjects with low fan-
tasy proneness might be less emotional reactivity; (3) CL can simulate
the emotion undermodulation of DID. However, if these latter 2 fea-
tures of CL would apply, then a difference between the 2 control groups
should have been found in the neurobiological and psychophysiologi-
cal data. As neither was the case, future studies should investigate the
fantasy-prone dependent activation of bilateral superior frontal regions.
Results of the within-TPS comparison of brain reactivity on the
differential processing of trauma-related and neutral MS and between-
personality state–dependent processing of the trauma-related text have
been discussed before (Reinders et al., 2012). The findings were re-
ported here only to inform on the brain activation patterns entering
the conjunction analyses. Most of the (de)activated brain regions were
independent of fantasy proneness as they were found in both the DID
versus CH and the DID versus CL comparisons. Because brain activa-
tion in DID is independent of fantasy proneness, these results do not
support the fantasy model of DID.
Our model proposes that the dorsal striatum, which includes the
caudate nucleus, plays an important role in maintaining state stability of
a dissociative personality state (Reinders et al., 2014). In the between-
personality states comparison, we found caudate activation in TPS as
TABLE 4. (Continued)
Between Group
DID-CH DID-CL CH-CL
L/R Brain Region BA x y z T*kE x y z T*kE x y z T*kE
NPSn-TPSn
Cortical areas NS NS NS
Subcortical areas NS NS NS
Cerebellum NS NS NS
Overview of brain areas with statistically significant cerebral blood flow changes when comparing DID patients to high or low DID-simulating controlsubjects
(CH and CL, respectively) for the neutral and trauma-related MS effects between TPS (TPS: top) and NPSs (NPS: bottom). Results for the TPSt-NPSt and vice
versa (top part) have been published previously (Reinders et al., 2012) and are shown here for convenience as the conjunction analyses in Table 5 are dependent on
these comparisons.
*p< 0.05, corrected for multiple comparisons.
**p< 0.05, corrected for multiple comparisons for the whole brain.
L/R indicates left/right; M, middle; S, superior; X, midline.
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TABLE 5. Psychophysiological Results: MS Effects Between Dissociative Personality States
Processing of the Trauma-Related Text Processing of the Neutral Text
DID (TPSt-NPSt) >
CH (TPSt-NPSt)
DID (TPSt-NPSt) >
CL (TPSt-NPSt)
CH (TPSt-NPSt) >
CL (TPSt-NPSt)
DID (TPSn-NPSn) >
CH (TPSn-NPSn)
DID (TPSn-NPSn) >
CL (TPSn-NPSn)
CH (TPSn-NPSn) >
CL (TPSn-NPSn)
Subjective ratings
Sensory rating F
1,20
= 20.33, p<0.001
a
F
1,18
= 13.06, p= 0.002
a
NS NS NS F
1,17
=6.95,p= 0.018*
DID (mean, 4.10; SD, 2.38) DID (mean, 4.10; SD, 2.38) CH (mean, 0.62; SD, 0.56) DID (mean, 0.30; SD, 0.64) DID (mean, 0.30; SD, 0.64) CH (mean, 0.01; SD, 0.33)
CH (mean, 0.62; SD, 0.56) CL (mean, 0.96; SD, 0.65) CL (mean, 0.96; SD, 0.65) CH (mean, 0.01; SD, 0.33) CL (mean, 0.47; SD, 0.41) CL (mean, 0.47; SD, 0.41)
Emotional rating NS^ F
1,18
= 4.61, p= 0.046* NS NS NS NS
DID (mean, 4.21; SD, 3.05) DID (mean, 4.21; SD, 3.05) CH (mean, 2.07; SD, 1.45) DID (mean, 0.11; SD, 0.31) DID (mean, 0.11; SD, 0.31) CH (mean, 0.45; SD, 0.89)
CH (mean, 2.07; SD, 1.45) CL (mean, 1.67; SD, 1.59) CL (mean, 1.67; SD, 1.59) CH (mean, 0.45; SD, 0.89) CL (mean, 0.33; SD, 0.52) CL (mean, 0.33; SD, 0.52)
Autonomic reactions
Heart rate
frequency
F
1,20
= 11.55, p=0.003
a
F
1,18
= 9.95, p= 0.006* NS NS NS NS
DID (mean, 9.64; SD, 8.39) DID (mean, 9.64; SD, 8.39) CH (mean, −0.08; SD, 3.50) DID (mean, 1.18; SD, 4.71) DID (mean, 1.18; SD, 4.71) CH (mean, −1.17; SD, 2.55)
CH (mean, −0.08; SD, 3.50) CL (mean, −0.21; SD, 3.01) CL (mean, −0.21; SD, 3.01) CH (mean, −1.17; SD, 2.55) CL (mean, −0.29; SD, 2.96) CL (mean, −0.29; SD, 2.96)
Systolic blood
pressure
F
1,20
=9.11,p=0.007* F
1,18
= 4.86, p= 0.042* NS NS NS NS
DID (mean, 10.45; SD, 11.92) DID (mean, 10.45; SD, 11.92) CH (mean, −1.25; SD, 2.89) DID (mean, 2.00; SD, 6.23) DID (mean, 2.00; SD, 6.23) CH (mean, −0.48; SD, 4.14)
CH (mean, −1.25; SD, 2.89) CL (mean, 0.63; SD, 4.54) CL (mean, 0.63; SD, 4.54) CH (mean, −0.48; SD, 4.14) CL (mean, −1.96; SD, 4.43) CL (mean, −1.96; SD, 4.43)
Diastolic blood
pressure
NS NS NS NS NS NS
DID (mean, 3.59; SD, 7.59) DID (mean, 3.59; SD, 7.59) CH (mean, 0.47; SD, 3.66) DID (mean, 1.14; SD, 4.17) DID (mean, 1.14; SD, 4.17) CH (mean, 1.12; SD, 2.66)
CH (mean, 0.47; SD, 3.66) CL (mean, 1.38; SD, 1.70) CL (mean, 1.38; SD, 1.70) CH (mean, 1.12; SD, 2.66) CL (mean, −0.71; SD, 2.33) CL (mean, −0.71; SD, 2.33)
HRV average F
1,19
=5.66,p=0.029* F
1,17
= 4.65, p= 0.047* NS NS NS NS
DID (mean, −70.79; SD, 86.37) DID (mean, −70.79; SD, 86.37) CH (mean, 2.20; SD, 34.11) DID (mean, 12.67; SD, 43.26) DID (mean, 12.67; SD, 43.26) CH (mean, 8.46; SD, 34.03)
CH (mean, 2.20; SD, 34.11) CL (mean, 2.19; SD, 24.99) CL (mean, 2.19; SD, 24.99) CH (mean, 8.46; SD, 34.03) CL (mean, −2.65; SD, 32.57) CL (mean, −2.65; SD, 32.57)
This table shows the results for the post hoc tests between the 3 groups for the between dissociative personality state processing of the trauma-related text and the processing of the neutral text. As hypotheses were
1 sided, only 1 directional test was performed and reported here.
a
Corrected for multiple comparisons.
*p< 0.05 uncorrected for multiple comparisons.
NS indicates not statistically significant; NS^, trend: 0.05 < p< 0.10 uncorrected.
The Journal of Nervous and Mental Disease •Volume 00, Number 00, Month 2016 Psychobiology of DID: Full Monty
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TABLE 6. Neurobiological Results: Conjunction Analyses of the Within and Between Dissociative Personality State Comparisons
L/R Brain Region BA
Conjunction 2 Groups Conjunction 3 Groups
DID and CH DID and CL DID and CH and CL
xyzT*kE x y z T*kE x y z T*kE
Within-personality states
TPSt-TPSn
Cortical areas NS NS NS
Subcortical areas NS NS NS
Cerebellum NS NS NS
TPSn-TPSt
Cortical areas NS NS NS
Subcortical areas NS NS NS
Cerebellum NS NS NS
NPSt-NPSn
Cortical areas NS NS
R Primary auditory cortex BA 41/42 42 −18 26 2.47 637
R M. frontal gyrus BA 9 24 30 20 2.45 212
Subcortical areas NS NS NS
Cerebellum NS NS NS
NPSn-NPSt
Cortical areas NS
R M. temporal gyrus BA 21 58 −54 −12 3.14 427 62 −50 −12 2.30 431
L I. temporal gyrus BA 37 −56 −52 −28 2.83 104 −56 −54 −32 2.38 307
R Occipitotemporal sulcus BA 20 38 −30 −24 2.75 190
Subcortical areas NS NS NS
Cerebellum NS NS NS
Between-personality states
TPSt-NPSt
Cortical areas NS NS
L Orbitofrontal cortex BA 11 −34 30 −24 3.14 175
L M. temporal gyrus BA 21 −42 0 −22 2.48 107
L S. temporal gyrus BA 38 −52 18 −16 2.30 34
R Occipitotemporal sulcus BA 20 38 −14 −24 2.34 24
Subcortical areas NS NS
LAmygdala −12 4 −24 3.52 1281
Cerebellum NS NS
L Cerebellum −10 −48 −32 3.18 253
NPSt-TPSt
Cortical areas NS NS
R Precentral gyrus BA 6 44 0 50 3.22 414
Subcortical areas NS NS NS
Cerebellum NS NS NS
TPSn-NPSn
Cortical areas NS NS NS
Subcortical areas NS NS NS
Cerebellum NS NS NS
NPSn-TPSn
Cortical areas NS NS NS
Subcortical areas NS NS NS
Cerebellum NS NS NS
Overview of brain areas with statistically significant cerebral blood flow changes when investigating conjoint activations in the DID patients and the high
and/or low DID-simulating control subjects (CH or/and CL) for the neutral and trauma-related MS effects within and between neutral and trauma-related dis-
sociative personality states.
*p< 0.05, corrected for multiple comparisons for the whole brain.
I indicates inferior; L/R, left/right; M, middle; S, superior.
Reinders et al. The Journal of Nervous and Mental Disease •Volume 00, Number 00, Month 2016
10 www.jonmd.com © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Copyright © 2016 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
compared with NPS in DID as compared with CH and CL during the
processing of the neutral text. This finding is independent of emotional
reactivity in TPS because no significant differences were found for ei-
ther of the subjective or the autonomic measures. We therefore propose
that the caudate nucleus plays an important role inmaintaining state sta-
bility of a dissociative personality state. A recent neurostructural study
(Chalavi et al., 2015a) reported a positive correlation between dorsal
striatal volume and clinical measures of dissociation, which also indi-
cates the involvement of the dorsal striatum in the psychopathology
of DID.
As a third new line of analyses, we compared both control
groups to each other to inform on the neural correlates of fantasy prone-
ness. We found the right hippocampus and the left amygdala and cere-
bellum. Of these findings, the hippocampus is the most interesting
because when mentally healthy individuals recollect autobiographical
experiences the hippocampus becomes involved (Rugg and Vilberg,
2013). Our neurobiological model for DID proposes that acute stress
can be associated with a shift from hippocampal involvement to caudate
nucleus involvement (Reinders et al., 2014). Thus, acute stress is linked
with a caudate nucleus-dependent stimulus-response at the expense of
hippocampal dependent spatial learning and memory (Schwabe et al.,
2008; White, 2009). The current analysis did show differential hippo-
campal activation between the control groups, but not caudate activa-
tion. Bilateral caudate nucleus activation was found for DID patients
who listened to the trauma MSs as TPS when compared with CH or
CL. These new f indings support our model that the caudate and not hip-
pocampus plays an important role in trauma-related memory retrieval in
DID. Furthermore, we found caudate activation in TPS as compared
with NPS in DID as compared with CH and CL during the processing
of the neutral text and proposed a role for the caudate nucleus in main-
taining state stability of a dissociative personality state. This dual in-
volvement of the caudate nucleus in the neurobiology DID needs to
be further studied in future research.
Testing for commonalities in brain activation between DID and
CH did not reveal any overlap in brain activation patterns for both the
within- and between-personality state comparisons, which opposes
the fantasy model. In our previous article (Reinders et al., 2012), we
proposed that CL simulated DID slightly better on a neural level than
CH. The new conjunction analyses confirm this suggestion because
the conjunction analyses between DID and CL revealed some con-
jointly activated brain regions. It seems that fantasy proneness is not a
major factor in the etiology of DID because our results are in the oppo-
site direction as predicted by the fantasy model. Hence, the results of
these new conjunction analyses provide an important contribution to
the etiology discussion.
Furthermore, it is important to note (top section of Table 4) that
the control subjects are unable to simulate TPS in that there is no over-
lap in brain activation, but that they are able to partly simulate NPS.
Conjoint activation in the 3 groups was found in the right primary audi-
tory cortex, the right frontal, and bilateral temporal regions for the
within-NPS comparison only. This is consistent with the notion that
NPS functions in some regard as “normal.”Taking further into account
the second half of Table 4, we note that the majority of the conjointly
(de)activated regions between DID and CL (bilateral temporal gyrus,
right occipitotemporal gyrus, left orbitofrontal, left amygdala, left cer-
ebellum, and right precentral gyrus) are not included in the neurobio-
logical model of DID. In addition, pivotal key regions involved in
the regulation of hypoarousal in NPS (such as the prefrontal cortex,
cingulate, the posterior association areas, and the parahippocampal
gyri) and of hyperarousal in TPS (such as the insula as well as the dor-
sal striatum) in DID were notfound in the control groups. These results
do not support the fantasy model. We propose that the conjointly (de)
activated areas do not play a role in the DID symptoms or emotion
modulation/regulation. The conjointly (de)activated regions may be
assigned to general task performance, such as listening to, and early
processing of, the auditory presented information, as well as function-
ing relatively “normal.”
Limitations are as follows: no validated quantitative trait and
state dissociative symptom measures were obtained, the data were used
for previous publications, information on specific psychiatric comor-
bidities of the DID patients is not available, practice of DID simulation
was relatively brief, and only a limited number of patients were in-
cluded. Nevertheless, to date, our study is the only study investigating
personality state–dependent brain activation in response to autobiograph-
ical texts, while controlling for motivated role playing. We recommend
that future studies include larger sample sizes. Furthermore, our findings
cannot be extended to DID populations in general as only female patients
and control subjects participated in the study, even though the DID pop-
ulation consists mainly of females. Of note, a same-sex study does not
suffer from sex differences (Bell et al., 2006). Despite these limitations,
our findings concur with the study’s initial a priori hypothesis that
high-fantasy-prone mentally healthy control subjects are unable to sim-
ulate DID. Overall, our results contradict the fantasy model.
In conclusion, by presenting results of new exploratory analyses,
we answer to calls for more neurobiological information concerning
dissociation from proponents of both the fantasy and trauma models.
The results offer new information concerning the etiology of DID. This
is important because empirical research into DID is still in an early
phase. Results of the new post hoc ttests on the psychophysiological
measures confirm the trauma model of DID. Results obtained from
the brain data do not support the fantasy model of DID.
ACKNOWLEDGMENTS
The authors thank all the participants. They also thank Margo
Jongsma for herassistance and participant recruitment. Jaap Haaksma
is thanked for the HRV data collection. Borden Armstrong is thanked for
psychophysiological data analysis support and proofreading, and Sima
Chalavi for editing the tables.
DISCLOSURE
A.A.T.S.R. was supported by the Netherlands Organization for
Scientific Research (www.nwo.nl), NWO-VENI grant 451-07-009.
The authors declare no conflict of interest.
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