65 (2009) 38–46www.elsevier.com/locate/psychres

Psychiatry Research 1

Schizophrenia with obsessive-compulsive disorder andobsessive-compulsive disorder with poor insight:

A neuropsychological comparison

Selim Tumkaya, Filiz Karadag ⁎, Nalan K. Oguzhanoglu, Cigdem Tekkanat,Gulfizar Varma, Osman Ozdel, Figen Ateşçi

Pamukkale University, Faculty of Medicine, Psychiatry Department, Denizli, Turkey

Received 19 April 2007; received in revised form 13 July 2007; accepted 16 July 2007

Abstract

Schizophrenia patients with obsessive-compulsive disorder (OCD)may be a subgroup of schizophrenia, andOCD patients with poorinsight may show psychotic-like symptoms. The aim of this work is to compare the neuropsychological performance of those patientswith schizophrenic patients who do not haveOCD symptoms andwithOCD patients who have good insight. The sample consisted of 89patients (16OCD-schizophrenic patients, 30 non-OCD schizophrenic patients, 30OCDpatients with good insight, 13OCDpatientswithpoor insight). Neuropsychological evaluation included executive functions, verbal and visual memory and attention tasks. Whileschizophrenic patients with OCD did not differ from the non-OCD schizophrenia and OCDwith poor insight groups on long-term visualand verbal memory performance, they showed poorer performance than the OCD group on long-term visual and verbal memory tests.Considering executive function, the OCD group with poor insight performed significantly worse than their counterparts with goodinsight, and the latter group performed better than the schizophrenia patients. The results of this study suggest that the neuropsychologicalperformance of schizophrenia patients with OCD did not differ from that of non-OCD schizophrenic patients, and that OCD patients withpoor insight were more likely to share similar cognitive characteristics with the schizophrenia groups. Our results also provideneuropsychological support for the hypothesis that OCD and schizophrenia may be a spectrum disorders.© 2007 Elsevier Ireland Ltd. All rights reserved.

Keywords: Psychotic disorders; Obsessive-compulsive symptoms; Neuropsychology; Comorbidity; Executive function; Memory; Insight

1. Introduction

The prevalence of obsessive-compulsive (OC) symp-toms in schizophrenia is higher than in the generalpopulation and has recently been reported as ranging bet-ween 7.8% and 55%. There is a considerable overlap

⁎ Corresponding author. Pamukkale Universitesi, Tip Fakultesi,Psikiyatri, AD, Doktorlar Cd, 20100, Denizli Turkey. Tel.: +902582410034/612.

E-mail address: filizlal@yahoo.com (F. Karadag).

0165-1781/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights resedoi:10.1016/j.psychres.2007.07.031

between schizophrenia and obsessive-compulsive disor-der (OCD) in the structural and functional brain abnor-malities and in the neurotransmitter systems involved, andalso in several demographic and clinical characteristics(Bland et al., 1987; Eisen et al., 1997; Poyurovsky et al.,1999; Tibbo et al., 2000; Nechmad et al., 2003; Bottaset al., 2005).Although it remains at present a controversialissue, epidemiologic and neurobiologic evidence suggeststhat schizophrenia patients with comorbid OCD mayrepresent a special category among patients withschizophrenia. The current literature strongly indicates

rved.

39S. Tumkaya et al. / Psychiatry Research 165 (2009) 38–46

that cognitive deficits are an important dimensionof schizophrenia. The most common cognitive deficitsfound in schizophrenia are impaired verbal learning andmemory, and executive function. The use of an increas-ingly refined neuropsychological task has implied thattheremay be specific patterns of neurocognitive deficits inschizophrenia or its subtypes (Crow, 1980). Neuropsy-chological studies comparing the performance of schizo-phrenia patients with or without OC symptoms are stilllimited and their results are contradictory. Certain studieshave shown that schizophrenia patients with OC symp-toms perform worse than schizophrenia patients withoutOC symptoms on some neuropsychological tests, in-cluding measures of memory and executive functioning(Lysaker et al., 2000; Hwang et al., 2000; Lysaker et al.,2002), while others have reported no difference (Whitneyet al., 2004; Bottas et al., 2005; Öngür and Goff, 2005).The differences between OCD and schizophrenia seem tobe related to thought disorders involving obsessions,overvalued ideas and delusions. Although obsessionshave been defined as ideas that the affected personperceives as absurd and irrational, certain patientswith OCD perceive their obsessions as rational and donot resist their symptoms. The existing literature hasdefined these patients as suffering from “atypical OCD”,“obsessive psychosis”, or “schizo-obsessive disorder”(Solyom et al., 1985; Kozak and Foa, 1994). The term“overvalued ideas” has frequently been used to explainthe OC symptoms of this patient population. Overvaluedideas differ from delusions in a slight increase in severity;they differ from obsessions in not being seen asunreasonable and, therefore, in not being resisted. Over-valued ideas are viewed by the patients as realistic, areassociatedwith amore severe illness, a chronic course anda worse response to treatment (Eisen and Rasmussen,1993; Kozak and Foa, 1994; Ravi Kishore et al., 2004;Neziroğlu et al., 2004; Bellino et al., 2005). The conceptof overvalued ideas in OCD can be considered asequivalent to an identifier of “OCD with poor insight”,as provided by the DSM-IV classification (AmericanPsychiatric Association, 1994). Although the DSM-IVclassification regards OCDwith poor insight as an anxietydisorder, some studies have emphasized its psychoticdimension (Kozak and Foa, 1994; American PsychiatricAssociation, 1994). Impairment of visual memory inpatients with OCD is a more consistent neuro-psychological finding (Aouizerate et al., 2004). Althoughit has generally been reported that executive functions areintact in OCD, impaired executive functions have beenfound when comorbid schizotypal features exist (Harrisand Dinn, 2003). The available data about the neuropsy-chological features of OCD with poor insight are limited.

More recently Kitiş et al. (2007) have reported thatovervalued ideas in OCD may be related to cognitivedysfunctions in OCD and this subtype of OCD may havesimilar characteristics to schizophrenia in terms ofcognition.

Based on this background, our study has two majorhypotheses: First, the neuropsychological performancesof OCD-schizophrenic patients differ from those of theirnon-OCD counterparts and, second, if OCD-schizophren-ic patients represent a distinct subtype, they should beexpected to show neuropsychological characteristicssimilar to those of OCD patients, including patients withgood or poor insight. Although the psychotic dimensionof OCD with poor insight has been emphasized, thereis little investigation into this population. Therefore,we also compared the neuropsychological performanceof these patients with OCD-schizophrenic patients, non-OCD schizophrenic patients, andOCDpatients with goodinsight.

The methodological advantages of the present studyover previous ones are as follows: To study a samplewith ahomogeneous level of OC symptom severity, we includedin the OCD-schizophrenia group those patients who metthe DSM-IV diagnostic criteria for both schizophreniaand OCD. Secondly, our use of an objective measure-ment of insight (based on OVIS scores) provided us with amore objective definition of the OCD with poor insightgroup.

2. Methods

2.1. Subjects

This study was performed on patients who applied tothe out-patients services or who have been followed bythe anxiety disorders and psychotic disorder sections ofPamukkale University, Medical Faculty, PsychiatryDepartment. The study was approved by the EthicsCommittee of the Pamukkale UniversityMedical Faculty.One hundred and one patients who gave informed consentwere enrolled into the study between September 2005 andJuly 2006. The exclusion criteria were as follows: mentalretardation, having significant neurological and medicalillness, being illiterate, acute psychosis and ECTtreatment within the previous 6 months.

2.2. Procedures

The data were collected in two interviews. The firstinterview focused on sociodemographic data, clinicalcharacteristics, and the psychiatric diagnosis of thepatients. Psychiatric diagnoses were established through

40 S. Tumkaya et al. / Psychiatry Research 165 (2009) 38–46

the Structured Clinical Interview for DSM-IV, ClinicalVersion (SCID-I) (First et al., 1997). Schizophrenia,schizophrenia+OCD, and OCD groups were determined,using the SCID interview. The patients who fulfilledthe DSM-IV criteria for both disorders were included inthe schizophrenia+OCD group. To avoid the possiblyconfounding effect of severe depressive symptoms onneuropsychological performance, nine patients diagnosedas having suffering from major depressive episodes wereexcluded from the study. Following this, the clinical ratingscales were administered: The severity of positive andnegative symptoms was assessed using the Scale forthe Assessment of Positive Symptoms (SAPS) and theScale for the Assessment of Negative Symptoms (SANS)(Andreasen, 1990). The severity of OCD symptoms wasexamined using the Yale-Brown Obsessive CompulsiveScale (Y-BOCS) (Goodman et al., 1989). The reliabilityand validity study demonstrated excellent inter-raterreliability in the Turkish version of the Y-BOCS (Teket al., 1995). The severity of depressive symptoms wasassessed with the Calgary Depression Scale in schizo-phrenia (Addington et al., 1990) (CDS) for the schizo-phrenia and schizophrenia+OCD groups and with theHamilton Depression Rating Scale (HDRS, Hamilton,1967) for the OCD group. The reliability and validitystudies of the Turkish version of the CDSwere performedby Aydemir et al. (2000) and of the HDRS by Akdemiret al. (2001). The Over Valued Ideas Scale (OVIS) wasused to describe the OCD patients with poor insight(Neziroğlu et al., 1999). TheOVIS is an 11-item clinician-administered scale to assess the severity of overvaluedideation. Overvalued ideas are assessed on severaldifferent continua: the strength of the belief, howreasonable the belief is, the strongest and the weakestthe belief has been over the past week, the accuracy of thebelief, the extent to which others share the same belief,how the patient attributes similar or differing beliefs toother people, how effective and important the patient'scompulsions are in preventing negative consequences, theextent to which the patient's OCD has caused the obses-sive belief, and the patient's degree of resistance towardthe belief. Scores on the OVIS range from 0 to 10, withhigher scores representing more overvalued ideas. In therelevant literature, overvalued ideas have been consideredas a reliable representation of poor insight in OCD. In thepresent study, we categorized patients with OVIS scoresof 6 or above as OCD with poor insight (Neziroğlu et al.,2004).

Within 1 week after the first interview, neuropsy-chological tests were performed by a clinical psychol-ogist without knowledge of psychiatric diagnoses andclinical rating scale scores. The neuropsychological

examination included the Digit Span Test, WechslerVisual Memory Test, Wisconsin Card Sorting Test, andVerbal Memory Processes Test. Three patients did notcomplete the testing procedure. Thus, the final sampleconsisted of 89 patients (42 female, 47 male, rangingin age from 17 to 63): 30 schizophrenia patients, 16schizophrenia and OCD patients (SCH+OCD), 30 OCDpatients, and 13 OCD patients with poor insight.

2.3. Neuropsychological tests

Neuro-cognitive evaluation was included in thefollowing neuropsychological tests. All participants weretested individually.

2.3.1. Memory: (short-term and long-term)

2.3.1.1. Verbal memory. The Verbal Memory ProcessesTest (VMPT) is an: This test is an analogue of the ReyAuditory Verbal Learning test in the Turkish language,which was developed by Öktem–Tanor. It uses a 15-wordlist that is read to the subject 10 times. The VMPTprovides different measures: learning (i.e., registrationand acquisition, acquisition being a measure of increase inregistered items over trials) and short-term recall, delayedrecall, and inconsistency scores that assess an impairmentof memory organization (Öktem–Tanor, 1992).

2.3.1.2. Visual memory. Visual memory was exam-ined with the Visual Reproduction (VR) test. This testwas developed by Wechsler and uses a subtest of theWMS (Wechsler Memory Scale). It includes cards withfour different designs. Each design is shown for 10 s.Following each exposure, subjects draw what theyremember of the design. A delayed recall trial is givenfollowing a 30-min delay (Wechsler, 1981).

2.3.2. Executive functions and attentionIn the Digit Span Subtest (Wechsler Adult Intelli-

gence Scale) (Lezak, 1995), the subject repeats a fixedrandom series of numbers of increasing length in directorder (digits forward) and in reverse order (digitsbackward). In addition to auditory attention and short-term retention capacity, this test assesses the ability tomanipulate the information in verbal working memory.Standardized scores were calculated as described inthe manual, by using raw scores for direct and reverseorder.

TheWisconsin Card Sorting Test (WCST) was used toexamine persistence, strategic planning, category shifting,mental control, and organization (Heaton et al., 1993).Total errors, number of achieved categories, number of

41S. Tumkaya et al. / Psychiatry Research 165 (2009) 38–46

perseverative responses, number of perseverative errors,and number of conceptual level responses are used in thisstudy.

The Stroop test (Dotrill format) was used to evaluateselective attention, ability of attentional set shifting andresponse inhibition. There were two trials, one in whichreading focused on color words printed in ink of differentcolors, and the other requiring naming of the printedcolors. For each part, both completion time and numberof errors were recorded (Stroop, 1935; Lezak, 1995).

The Trail Making Test (TMT) assesses sequencing,attention, mental flexibility, and the speed of visualsearch and of motor function. It consists of two parts(Parts A–B). The key measures are the time (in seconds)needed by the patient to complete each part of thetest (Reitan, 1993). Score differences between TMT-Aand TMT-B (B–A) are taken into consideration in thisstudy.

2.4. Statistical analysis

For continuous variables (age, illness duration, clinicalrating scores, neuropsychological test scores), in orderto examine the differences among patients groups, dueto the unequal sample size for each group and inequalityof variance for the numerous variables, we performed

Table 1Demographic and clinical characteristics of the patient groups

Groups (n) OCD (30) OCDPI (13) S

GenderFemale n (%) 17 (56.7) 7 (53.8) 5Male n (%) 13 (43.3) 6 (46.2) 1

Marital statusMarried n (%) 18 (60) 5 (38.5%) 3Single n (%) 12 (40) 8 (61.5%) 1

Mean (S.D.) Mean (S.D.) MAge 33.26 (11.74) 34.61 (13.75) 3Education (years) 10.50 (3.74) 12.30 (3.11) 1Age of onset 23.86 (9.23) 28.30(11.37) 2Illness duration (years) 9.40 (9.24) 6.30 (5.76) 1N of hospitalization 0.23 (0.67) 0.30 (0.85) 1Y-BOCS Obsession 9.86 (5.30) 12.69 (5.42) 1Y-BOCS Compulsion 8.20 (5.33) 9.07 (6.22) 1SANS 5SAPS 3CDS 6HDRS 8.33 (5.55) 10.30 (4.04)OVIS 3.46 (1.09) 7.51 (0.73) 5

OCD: obsessive-compulsive disorder, OCDPI: OCD with poor insight, SCHa Test statistics (degrees of freedom).b Chi Square test.c Kruskal-Wallis analysis of variance test.d Mann-Whitney U Test.

Kruskal-Wallis variance analysis, a non-parametricequivalent of variance analysis. Significant group differ-ences on the Kruskal-Wallis variance analysis were alsoreanalysed using Mann-Whitney U tests with Bonferronicorrection as post-hoc analysis. For categorical variables(gender, marital status) the differences among the groupswere analysed with the Chi Square Test. Relationshipsbetween the numerous clinical symptoms and neuropsy-chological test scores were evaluated via PearsonCorrelation Analysis. The data analyses were carried outwith the SPSS program, 10.0 Version for Windows.

3. Results

3.1. Demographic and clinical characteristics

The demographic and clinical characteristics of thefour patient groups are presented in Table 1. The groupswere not significantly different with respect to theirdemographic characteristics such as age, gender, educa-tion levels or marital status.

The schizophrenic patients had a significantly longerduration of illness than the OCD and OCD with poorinsight groups (respectivelyU=281.5, P=0.013;U=79.0,P=0.002, Mann-Whitney U test). The schizophreniaand schizophrenia+OCD groups showed no significant

CH+OCD(16) SCH (n: 30) df a P

(31.3) 13 (43.3)1 (68.8) 17 (56.7) 3.12 (1) b 0.373

(18.8%) 13 (43.3%)3 (81.3%) 17 (56.7%) 7.43 (1) b 0.059

ean (S.D.) Mean (S.D.)3.37 (13.37) 38.63 (10.72) 2.19 (3) c 0.1760.81 (3.16) 11.00 (3.41) 4.94 (3) c 0.5321.37 (7.65) 24.06 (7.13) 4.99 (3) c 0.1722.00 (11.10) 14.56 (8.54) 11.28 (3) c 0.01.93 (2.51) 3.50 (3.56) 38.46 (3) c 0.002.31 (4.45) 2.70 (2) c 0.2580.68 (4.52) 0.96 (2) c 0.6191.68 (23.18) 56.33 (18.40) 0.56 d 0.5721.37 (10.61) 42.53 (23.00) 1.62 d 0.104.81 (3.98) 5.36 (3.81) 1.22 d 0.222

1.26 d 0.739.43 (1.70) 35.73 b 0.00

+OCD: comorbid schizophrenia and OCD, SCH: schizophrenia.

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differences in their SANS and SAPS scores. The OCD,OCDPI and SCH+OCD groups were not significantlydifferent in their Y-BOCS obsession and compulsionscores. The severity of depressive symptoms was also notdifferent among groups. As expected, the OCD with poorinsight group had significantly higher OVIS scores than theOCD group (U=0.000, P=0.000, Mann-Whitney U test)and, interestingly, the OVIS score of the schizophrenia+OCD group was significantly lower than that of the OCDwith poor insight group (U=27.5, P=0.001, Mann-Whitney U test).

For the SCH+OCD group, the onset of OCD precededthe presentation of the overt psychotic symptoms andestablished schizophrenia diagnosis in 10 patients. Two ofthem were drug-free; the ongoing medications of theremaining patients were as follows: 3 olanzapine, 2olanzapine and SSRI, and one each risperidone, risper-idone and SSRI, quetiapine and SRRI. The presentation ofOCD symptoms in six patients followed the diagnosis ofschizophrenia. Two of them were being treated with arisperidone-SSRI combination, and the others (one each)were receiving olanzapine-ziprasidone, quetiapine-risper-idone, and amisulpiride-tricyclic antidepressant combina-

Table 2Comparison of neuropsychological performance in the patient groups

OCD OCD PI SCH+OCD SCH

Median Median Median Median

WCSTTotal errors (n) 52.50 65.00 67.50 80.00Achieved categories (n) 3.00 3.00 2.00 1.00Perseverative responses (n) 14.50 24.00 46.50 61.00Perseverative errors (n) 10.50 22.00 39.50 50.41Conceptual responses (n) 57.00 40.00 42.00 24.36

SCWTWord reading 26.00 28.00 32.00 28.00Color naming 68.00 73.00 90.50 86.00Interference 38.00 47.00 57.50 56.50

TMTB–A 30.00 75.00 65.50 87.50

WMS-visual memoryImmediate recall 12.50 11.00 9.00 9.00Delayed recall 12.00 11.00 9.50 7.00

VMPTShort-term memory 5.00 5.00 5.00 4.00Learning 15.00 13.00 11.50 10.00Inconsistency 5.50 8.00 7.00 8.00Delayed free recall 12.00 11.00 9.00 8.00Digit span 6.00 7.00 7.00 6.00

OCD: obsessive-compulsive disorder, OCDPI: OCDwith poor insight, SCH+Wisconsin Card Sorting Test, SCWT: Stroop Color-Word Test, TMT: Trail MProcesses Test.

tions. None of these patients were being treated withclozapine, and their OCD symptoms were independent ofongoing medication status. Of the patients with schizo-phrenia, seven were on typical antipsychotics, 13 were onatypical antipsychotics (clozapine 1, risperidone 5,quetiapine 1, ziprasidone 3, and olanzapine 3) and 10were on combinations of typical and atypical antipsycho-tics (quetiapine 2, risperidone 4, clozapine 3, olanzapine 1).

Of the 30 patients with OCD, 9 were drug-free, 15were on selective serotonine reuptake inhibitors (SSRIs),4 were on tricyclic antidepressants (chlomipramine) and2 were on combinations of SSRIs and atypical anti-psychotics. Of the 13 OCD patients with poor insight, 3were drug-free, 2 were on SSRIs, 3 were on combinationsof SSRI and atypical antipsychotics, 3 were on combina-tions of tricyclic antidepressants and atypical antipsycho-tics, and 2 were on combinations of SSRIs and typicalantipsychotics.

3.2. Neuropsychological performance

Neuropsychological performance on different cogni-tive functions across patient groups is presented in Table 2.

Kruskal-Wallis test Significant post-hoc comparisons

χ2 (df: 3) P Mann-Whitney U test

15.951 0.001 SCHNOCD12.265 0.007 OCDNOCDPİNSCH18.981 0.000 SCHNOCD20.326 0.000 SCHNOCDNOCDPİ14.376 0.002 OCDNOCDPİNSCH

5.915 NS13.376 0.004 SCHNOCD13.327 0.004 SCHNOCD

18.749 0.000 SCHNOCDPİNOCD

13.769 0.003 OCDNSCH16.461 0.001 OCDNSCH+OCD NSCH

8.913 0.030 OCDNSCH16.827 0.001 OCDNSCH+OCDNSCH16.633 0.001 SCHNOCDPINOCD22.046 0.000 OCDNOCD+SCHNSCH1.183 0.757 NS

OCD: comorbid schizophrenia and OCD, SCH: schizophrenia, WCST:aking Test, WMS: Wechsler Memory Scale, VMPT: Verbal Memory

43S. Tumkaya et al. / Psychiatry Research 165 (2009) 38–46

3.2.1. Executive functionsTo make a clear presentation of the results, we also

summarized the results regarding executive function asa graph (Fig. 1). As shown in the table, the results of theKruskal-Wallis analysis of variance revealed significantdifferences among groups. Following this, a post-hoccomparison indicated that patients with schizophreniawere significantly impaired on almost all WCST indicescompared with the OCD and OCDPI groups. Theschizophrenia group achieved significantly fewer cate-gories (U=252.5, P=0.003), had fewer conceptuallevel responses (U=224.0, P=0.001) and more persev-erative errors (U=176.5, P=0.000) than the OCDgroups and the OCD with poor insight group (respec-tively; U=92.0, P=0.006 and U=93.0, P=0.007, all“P” values refer to the Mann-Whitney U test P value).

The performance of the SCH+OCD group on theWCST was not significantly different from that of theSCH group. The OCD and OCDPI groups also did notshow any significantly different performance on WCST.

The OCD group showed a better performance onthe Stroop Color-Word Test and the TMT than theschizophrenia group (on SCWT; color namingU=220.0, P=0.001, interference U=226.0, P=0.001,on TMT; B–A U=182.5, P=0.000; Mann-Whitney Utest). The performance of the schizophrenia group wasnot different from that of the OCDPI and OCD+SCHgroups on the Stroop and Trail Making Tests. TheOCDPI group had significantly worse performance onthe TMT than the OCD group (U=87.0, P=0.004,Mann-Whitney U test).

Fig. 1. Executive functions of the groups.

3.2.2. Memory and attentionMemory

Kruskal-Wallis analyses of variance showed signi-ficant group differences in the non-verbal and verbalmemory domain. The post-hoc comparisons of thegroups using the Mann-Whitney U test are summa-rized below.

Non-verbal memoryWhile the schizophrenia group showed worseperformance than the OCD group on visual memoryimmediate recall (U=210.0, P=0.000) and delayedrecall (U=200.0, P=0.000), the whereas SCH+OCD group displayed worse performance than theOCD group only on delayed recall (U=125.0,P=0.007). The OCD with poor insight group didnot significantly differ in visual memory perfor-mance from the other patient groups.

Verbal memoryThe schizophrenia group had significantly moredeficits than the OCD group on all verbal memoryand learning indices. The SCH+OCD group also hada worse performance than the OCD group in verballearning and delayed free recall. The OCD with poorinsight group significantly differed from the OCDgroup with a poor performance on inconsistencyscores. The OCD with poor insight group was notsignificantly different from the remaining groups onthe other verbal memory and learning indices.

AttentionNo significant differences across groups in the digitspan test were found. There were no significantcorrelations between neuropsychological performanceand the severity of positive symptoms (total score ofSAPS) in the schizophrenia and SCH+OCD groups.There was a significant but weak positive correlationbetween error scores on the WCST and severity ofnegative symptoms in the schizophrenia group(P=0.046, r=0.368). We did not find any significantcorrelation between neuropsychological performanceand Y-BOCS obsession and compulsion, HDRS, CDSand OVIS scores in the relevant patient groups.

4. Discussion

The co-occurrence of OC symptoms and schizophre-nia has been well known since the 19th century. Toour knowledge, the present study is the first attemptto compare neuropsychological profiles of OCD patientswith good or poor insight with schizophrenia patientswithand without OCD, that is, to try to cover all diagnosticentities which raise nosologic challenges for the putativeschizophrenia–OCD spectrum (Poyurovsky et al., 2004).

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In addition, a second strength of our work is the objec-tive measurement of insight using the OVIS. Most pre-vious studies have compared the demographic, clinical,neuroimaging and neuropsychological characteristicsof schizophrenic patients with vs. those without OCsymptoms, and of schizophrenic vs. OCD patients. Al-though more recently there is an increasing interest in theclinical difference between OCD with good vs. poorinsight, the data concerning neuropsychological perfor-mance are insufficient.

The main hypotheses of the current study, thatschizophrenic patients with co-morbid OCD wouldshow different neuropsychological features from schizo-phrenic patients without OCD and that they would becloser to OCD patients, have been partially supported byour findings. The schizophrenic patients with OCD didnot significantly differ from schizophrenic patientswithout OCD by neuropsychological profile; they alsodid not differ fromOCD patients with poor insight on anyof the executive and memory tests. However, schizophre-nia patients with OCD showed worse performance indelayed visual and verbal memory tests than did OCDpatients, regardless of degree of insight. The poor perfor-mance on the TMT was the single distinction betweenOCD patients with poor and good insight; in addition, theexecutive dysfunction of the OCDwith poor insight groupwas similar to that of the schizophrenia group except for abetter performance on WCST.

When reviewing the overall cognitive performancesof the studied groups, the schizophrenia group hasshown a more prominent disturbance of executivefunction than the other three groups, and the OCDgroup has fewer deficits than the remaining groupsaccording to our results. As graphically presented, thereis a gradual increase in cognitive dysfunction from OCDtoward OCD with poor insight, SCH+OCD andschizophrenia groups on executive function and mem-ory performance. The executive function performancesof OCD and schizophrenia patients were significantlydifferent. While executive dysfunction has been sug-gested as an essential feature of schizophrenia, execu-tive functions are relatively preserved in OCD patients,but not in patients with OCD with depression.(Abbruzzese et al., 1995; Bowie and Harvey, 2005;Henry, 2006). Our results support these observations.

Although some studies have reported that patientswith schizophrenia with OC symptoms had morecognitive dysfunction than other schizophrenia patients,other studies have reported no differences (Bermanet al., 1998; Lysaker et al., 2000; Hwang et al., 2000;Lysaker et al., 2002; Whitney et al., 2004; Öngür andGoff, 2005). Impaired performance on the WCST has

been the most commonly reported finding in schizo-phrenic patients with OC; findings of abnormality havebeen based on a higher rate of perseverative or non-perseverative errors, but the key components of theWCST that have been investigated have varied fromstudy to study, even in those carried out by the sameauthors (Lysaker et al., 2002, 2000). Lysaker et al. (2002),reported that schizophrenic patients with OC symptomsshowed marginally impaired executive function, asmeasured by WCST non-perseverative errors, vs.schizophrenic patients without OC symptoms. However,Lysaker et al. (2002) had earlier reported a greaterimpairment in schizophrenic patients with OC symptomsbased on WCST categories completed and percent ofperseverative. Hwang et al. (2000) also reported similarfindings in a sample with long inpatient stays, possiblyreflecting more deteriorated patients. Berman et al.(1998) found schizophrenia patients with significantOC symptoms were significantly impaired on delayedvisual memory but not on the WCST (categories com-pleted) or Trails A andB, as compared with those withoutsignificant OC symptoms. As for more recent studies, ourfindings have also suggested that schizophrenia patientswith OCDwere not distinguished non-OCD counterpartsby executive and memory dysfunction (Ohta et al., 2003;Hermesh et al., 2003; Öngür and Goff, 2005). At present,a relevant approach to these inconsistencies may be thatstated by Lysaker et al. (2002), whereby it is recognisedthat the data so far suggest that OC symptoms in schizo-phrenia spectrum disorders are linked with a distinctiveclinical picture, but the exact nature of that clinical pictureremains unclear.

The neuropsychological performance of the OCDwithpoor insight group was positioned between those of theOCD group and the schizophrenia group (Fig. 1). OCDpatients with poor insight were not significantly differentfrom the SCH+OCD group on any of the neuropsycho-logical tests; they also showed executive dysfunctionsimilar to that of the schizophrenia group except for asignificantly better performance on the WCST. Interest-ingly, OCD patients with poor insight showed significantdifferences from the OCD and schizophrenia groups oncertain executive measures. They differed from schizo-phrenia by a better performance on the WCST and fromOCD by a poor performance on the TMT. We found onlyone study which investigated the neuropsychological dys-functions in OCD patients with poor insight using theOVIS as a reliable measurement of insight (Kitiş et al.,2007). In this study, schizophrenia patients showed moreexecutive dysfunction compared with the OCD groupalthough the OCD patients with poor insight and theschizophrenia group did not differ with respect to

45S. Tumkaya et al. / Psychiatry Research 165 (2009) 38–46

executive functions. Our findings and those of Kitiş et al.converge in showing that the schizophrenia patientsand the OCD patients with poor insight shared certainexecutive dysfunction, but our study suggests that thesetwo groupsmay differ onWCST performance, contrary toKitiş et al.'s report that the schizophrenia group and theOCD with poor insight group showed the same impair-ments on all executive measures. Their mixed schizo-phrenia group (33.3% with OC symptoms versus 67.7%non-OC) may explain this inconsistency. The worsenedperformance of the schizophrenia group on the WCSTcompared with OCD with poor insight may be related tothe fact that WCST performance is a relatively specificindicator of dorsolateral prefrontal cortex function(Franke et al., 1992). Our results suggest that OCDpatients with poor insight may represent a distinct sub-group neuropsychologically, possibly reflecting a transi-tion between OCD and schizophrenia with regard toneuropsychological features.

As a result, our study has suggested that the schizo-phrenia patients with OCD did not show distinct neuro-psychological features. However, OCD patients with poorinsight, as compared with other OCD patients, have atendency to show neuropsychological deficits that aremore closely related to those in schizophrenia patientswith and without OCD. The most important clinicalimplication of our study is that OCD patients with poorinsight require more attention with respect to neuropsy-chological characteristics. The present study should, how-ever, be interpreted with caution because of severalmethodological limitations: (1) the relatively small samplesize within each diagnostic entity may have limited sensi-tivity to actual group differences and associations betweenneuropsychological functions and (2) inclusion of thepatients receiving different types of medication may beconsidered as a confounding factor. Because of ethical andpractical considerations, it is difficult to studymedication-free patients. Several studies have also reported that neu-ropsychological features of OCD and schizophrenia canbe considered to be independent of duration of psycho-pathology and medication (Addington et al., 1997;Mataix-Cols et al., 2002; Harvey et al., 2003; Roh et al.,2005). Another issue regarding medication is the de novoemergence or exacerbation of OCD symptoms withatypical antipsychotics, especially with clozapine, olan-zapine, risperidone and quetiapine in schizophreniapatients (Sareen et al., 2004; Mahendran et al., 2007). Inour SCH+OCDgroup no patients had received clozapine;also, their current OCD symptoms had not emergeddenovo or been exacerbated during ongoing atypi-cal antipsychotic treatment. Further studies with largesamples of first episode or drug-naïve patients may

provide more reliable and conclusive evidence regardingthe influence of medication.

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