Prevalence of Psychotic Disorders
in Patients with Obsessive-
Lieuwe de Haan, MD, PhD, Christine Dudek-Hodge, MD, PhD, Yolanda Verhoeven, MD,
and Damiaan Denys, MD, PhD
Dr. de Haan is assistant professor in the Department of Psychiatry at Academic Medical Centre in Amsterdam. Dr. Dudek-Hodge is a resident in the
Department of Psychiatry at Academic Medical Centre in Amsterdam. Dr. Verhoeven is a resident in the Department of Psychiatry at Academic Medical Centre
in Amsterdam. Dr. Denys is professor and head of the Department of Psychiatry at Academic Medical Centre in Amsterdam.
Faculty Disclosures: Dr. de Haan has received research/grant support from AstraZeneca and Eli Lilly; has received honoraria from Bristol-Meyers Squibb
and Janssen-Cilag. Dr. Dudek-Hodge, Dr. Verhoeven, and Dr. Denys report no affiliation with or financial interests in any organization that may pose a
conflict of interest.
Submitted for publication: December 24, 2008; Accepted for publication: June 22, 2009.
Please direct all correspondence to: Lieuwe de Haan, MD, PhD, Psychiatric Department, Academic Medical Center (AMC), Meibergdreef 5, 1105AZ
Amsterdam, The Netherlands; Tel: 31- 20-8913500; Fax: 31-20-8913702; E-mail: firstname.lastname@example.org.
CNS Spectr 14:8 © MBL Communications Inc.
Introduction: The co-occurrence of obses-
sive-compulsive disorder (OCD) in patients with
schizophrenia and related disorders has been
increasingly recognized. However, the rate of
psychosis comorbidity in OCD patients has yet to
be systematically evaluated.
Methods: The prevalence of the Diagnostic
and Statistical Manual of Mental Disorders,
Fourth Edition psychotic disorders was evalu-
ated in 757 subjects consecutively referred to a
specialised diagnostic and treatment facility for
OCD. Demographic and clinical characteristics
Results: Thirteen OCD patients (1.7%) also met
the DSM-IV criteria for a psychotic disorder. We
found no significant differences in clinical char-
acteristic between OCD patients with and with-
out a psychotic disorder, although patients with
OCD and a psychotic disorder more likely used
illicit substances and more likely were male.
• Relatively few patients referred to a specialized
obsessive-compulsive disorder (OCD) treatment
center suffer from a psychotic disorder.
• Treatment facilities dedicated to the care of psy-
chotic patients are more likely to be confronted
with psychosis and obsessive-compulsive symp-
toms (OCS) or OCD comorbidity.
• Research focused on the development of co-mor-
bid OCS and psychotic symptoms is needed.
Conclusion: Relatively few patients referred to
a specialized treatment OCD center suffer from a
CNS Spectr. 2009;14(8):415-417
Obsessive-compulsive symptoms (OCS) and
obsessive-compulsive disorder (OCD) are a
common comorbid condition in patients with
schizophrenia with a prevalence between 7%
OCS and OCD comorbidity in schizophrenic
patients has been the object of extensive
research in the last 10 years. This research
has led to the conclusion that OCS and OCD in
schizophrenic patients can be seen as a separate
category of schizophrenia, commonly referred to
as schizo-obsessive disorder.5,8-10
Surprisingly, little is known about the preva-
lence of psychotic disorders in patients with rec-
ognized OCD.1,11 In one study, the community
prevalence of psychotic disorder in OCS and
OCD patients has been found as high as 12%.12
Identification of psychotic disorders in OCD
patients may have prognostic and therapeutic
implications.6,13 There are distinct differences in
neurocognitive functioning and neurological soft
signs between OCD patients, schizo-obsessive
patients, and schizophrenia patients.7
In the present study we sought to determine
the prevalence of psychotic disorders in patients
referred to a specialized diagnostic and treatment
facility for OCD.
The study was conducted in a specialized
academic department dedicated to the diag-
nosis and treatment of OCD in Utrecht, The
Netherlands. All consecutively referred patients
underwent an extensive diagnostic protocol.
Diagnosis was based on the Structured Clinical
Interview for Diagnostic and Statistical Manual
of Mental Disorders, Fourth Edition Axis I
Disorders (SCID). Severity of OCD symptoms
was assessed with the Yale-Brown Obsessive
Compulsive Scale (Y-BOCS).14,15 All clinical
assessments were performed by experienced
and trained clinicians. The study was approved
by the institutional review boards and writ-
ten informed consent was obtained from the
patients after they received full explanations
regarding study procedures. Student’s t test and
χ-square test were used as appropriate.
Seven hundred fifty-seven subjects referred
from January 1, 2000 to January 1, 2006 were
included; 463 were female (62.3%). The mean
age at OCD onset for the total sample was 21.9
years of age (SD=3.2). Thirteen subjects, five
female, were diagnosed with a psychotic disor-
der (eight with schizophrenia, two with schizoaf-
fective disorder, three with psychotic disorder
not otherwise specified). Patients with OCD and
a psychotic disorder were more likely to be male
(P=.046) and to be a current drug user (P=.036).
However, only one patient from the OCD and
psychotic disorder group used cannabis and
only one used 3,4-methylenedioxymethamphet-
amine and we found no significant difference
in number of alcohol consumptions in the last
week between groups.
The global assessment of functioning scale
(GAF) was rated in all patients to assess overall
symptomatic and functional impairment. Mean
GAF score was 56.1 (SD=10.4). The severity of OCS
was rated for all patients using the Y-BOCS. Mean
score on the Y-BOCS was 23.9 (SD=7). No signifi-
cant differences were found in mean age at OCD
onset, Y-BOCS total score, obsessions or com-
pulsions subscale scores, or GAF at admission,
between OCD patients with and without comorbid
We found no significant differences in preceding
treatment with antidepressants or cognitive behav-
ioral therapy, although more patients with OCD
and a psychotic disorder received an antipsychotic
before referral (53.8% versus 13.3%, P=.005).
In the present study 1.7% of consecutively
referred patients to a specialized treatment OCD
center were diagnosed with a psychotic dis-
order according to DSM-IV. This finding is in
contrast with the results of most of the studies
examining the rate of OCD in schizophrenia pat
ients.1,4,5,11,16,17,18,19 Our results are in concordance
with the results from a recent study,20 but in
contrast with earlier research.12
One explanation for the low prevalence of
psychotic disorders in OCD patients is that the
time between the first OCS and the moment
of seeking help is on average 8 years.12 During
that time an emerging co morbid psychotic dis-
order would have led to clinical evaluation and
treatment in the majority of the patients. In that
case the patient would have been diagnosed
with a psychotic disorder and co morbid OCD.
The recent focus on early detection of first epi-
sode psychosis offers an explanation for the
lower prevalence of psychosis in OCD popula-
tions in more recent studies.2,4,5,21 Another rea-
son for the low prevalence of psychosis in OCD
patients referred for diagnosis and treatment
could be that the combination of OCD and psy-
chosis make patients less likely to seek help,
due to limited insight in their condition. This
would explain why in the community the preva-
lence of OCD and psychosis has been found as
high as 12%12 while in outpatient and clinical
CNS Spectr 14:8 © MBL Communications Inc. August 2009
setting it has been 0% to 1.7%.20 An explanation
of the higher prevalence of OCS and OCD in
patients with a primary diagnosis of psychosis
could be that treatment of psychosis induces
OCS or OCD in some patients.
The difference in substance use at admission
we found depends more on the relatively low
substance use rate of the OCD group (3.8%) than
on the high prevalence of substance use (15.4%)
in the group with OCD and a psychotic disorder.
Contrary to other studies, we did not find sig-
nificant differences between OCD patients and
OCD plus psychosis patients regarding OCD onset,
YBOCS total score, obsessions or compulsions
subscale scores or GAF scores at admission.7 ,22,23
There are several limitations to our study.
Although the study sample contained 757 indi-
viduals, the group with co morbid psychosis was
small and statistical analysis of between-group
differences have to be interpreted with caution.
As previously discussed, there is selec-
tion bias in our sample. Patients included in
the study were referred from other psychiatric
treatment facilities to a specialized clinic. It is
possible that psychotic disorders are more fre-
quently encountered in patients with OCD in
the community. However, we think it is unlikely
that the prevalence of psychotic disorders in
treated patients with OCD is much higher, since
patients with OCD and a psychotic disorder are
among the most difficult to treat and therefore,
as a group are more likely to be referred to a
specialized treatment center.
After systematic diagnostics according to
protocol we found that relatively few patients
referred to a specialized treatment OCD cen-
ter suffer from a psychotic disorder. This is
in strong contrast to earlier findings of high
comorbidity of OCD and psychosis in commu-
nity studies. CNS
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