Clinical correlates of obsessive-compulsive disorder comorbidity in patients with schizophrenia.

BACKGROUND/AIM: The primary aim of this study was to evaluate the clinical correlates of obsessive-compulsive disorder (OCD) comorbidity in patients with schizophrenia.
MATERIALS AND METHODS: This study included fifty schizophrenia patients with an existing OCD comorbidity and 200 schizophrenia patients who did not have an OCD diagnosis for a lifetime. The participants were administered Brief Psychiatric Rating Scale (BPRS), Clinical Global Impressions Severity Scale (CGI-S), Scale for the Assessment of Positive and Negative Symptoms (SAPS/SANS), Calgary Depression Scale for Schizophrenia (CDSS), Yale-Brown Obsessive Compulsive Scale, and Global Assessment of Functioning Scale.
RESULTS: Patients with OCD comorbidity had higher BPRS, SANS, and CGI-S scores compared to patients without OCD. In addition, patients with OCD showed worse functional impairment; however, sociodemographic variables, SAPS, CDSS, and insight scores did not show a significant difference depending on the presence of OCD. The present study also showed higher negative and depressive symptoms in patients with preexisting OCD compared to those manifesting OCD during the course of schizophrenia.
CONCLUSIONS: In this study, patients with schizophrenia and OCD comorbidity showed different clinical features compared to those not showing an OCD presence for a lifetime. In this study, positive symptoms were not determinative in the differentiation of patients with and without OCD. It is important to assess OCD symptoms in patients with schizophrenia, and psychosocial therapies should be provided in patients with OCD to improve negative symptoms and functionality. Patients with preexisting OCD displayed more severe symptoms and seemed to require a different clinical approach in treatment. Copyright:

INTRODUCTION

Although schizophrenia and obsessive-compulsive disorder (OCD) are distinct psychiatric disorders, OCD comorbidity manifests in a considerable number of patients with schizophrenia. The comorbidity rate of obsessive-compulsive symptoms (OCS) and OCD in patients with schizophrenia was reported as 10%–64% and 5%–50% in previous studies, respectively.[12] The etiology of OCD comorbidity in schizophrenia is not fully understood, and different explanations have been proposed for the high comorbidity rate.[3] The term “schizo-obsessive disorder” was used as a description in many research articles due to different clinical characteristics of schizophrenia patients with OCD comorbidity.[4] Despite the higher OCD rate in schizophrenia patients than in the general population (1%–2%), it remains unclear whether OCD comorbidity is a distinct subgroup of schizophrenia.[5]

Previous studies examining the impact of OCD on schizophrenia are controversial, demonstrating both severe or mild positive and negative symptoms and better or worse functionality.[678] Some studies suggest that an OCD diagnosis in schizophrenia is associated with poor clinical course, higher psychotic symptoms, and worse social impairment.[91011] However, some studies did not find any differences in these parameters with respect to OCD comorbidity.[612] Some studies found more severe negative symptoms in patients with schizophrenia with OCD comorbidity, whereas some suggested a positive relationship between the negative symptoms of schizophrenia and severe OCD symptoms.[1314]

Many studies reported lower functionality in patients with OCD; however, some studies found no difference between the functionality of patients with or without OCD.[1516] Contrary to many studies, some suggested better social functioning with OCD comorbidity, such as the studies by Tonna et al., which suggested better functioning with mild OCD severity after controlling for the impact of psychotic symptoms.[1718] The clinical correlates of OCD comorbidity in schizophrenia patients showed conflicting results between the studies, depending on different methodologies, use of different scales, and the characteristics of the patients included.

Some patients with schizophrenia present OCD features prior to their first psychotic episode or concurrently with psychotic symptoms at the onset of the illness, while a considerable number of patients manifest OCD comorbidity years after the onset of schizophrenia.[1920] Considering all the data, OCD comorbidity in schizophrenia showed distinct clinical features, and there is a great need for assessing and recognizing the clinical features of OCD comorbidity in schizophrenia.[21] In this study, we aimed to assess the clinical correlates of OCD comorbidity in patients with schizophrenia.

MATERIALS AND METHODS

Individuals aged between 18 and 60 years followed up with schizophrenia diagnosis according to the Diagnostic and Statistical Manual Disorders (DSM)-5 criteria at the outpatient psychiatry clinic of a university hospital and applied to the outpatient clinic between July and November 2018 were assessed for the study.[22] A total of 253 outpatients who did not have an OCD diagnosis for a lifetime were screened consecutively for inclusion into the study, and 48 patients (18 women and 30 men) were excluded from the study for the following reasons: missing answers in the clinical forms (n = 22), refusal to participate or give consent (n = 6), uncertainty about neurodevelopmental disorder comorbidity (n = 7), and inability to complete clinical evaluations (n = 13). Five patients, having scores between 8 and 15 on Yale–Brown Obsessive Compulsive Scale (YBOCS), were not included to the study to avoid the confounding effect of subthreshold OCD symptoms. Thus, 200 patients without an OCD diagnosis for a lifetime were enrolled in the study.[2223] A total of 59 outpatients with an existing OCD comorbidity according to the DSM-5 criteria were screened consecutively for inclusion into the study. Nine patients were excluded from the study for missing answers in the clinical forms or refusing to participate in the study and fifty patients with OCD were enrolled in the study. All participants with OCD had 16 or higher scores on YBOCS, whereas the individuals without OCD had 7 or lower scores during the assessment. Patients with organic brain disorders, mental retardation, neurodevelopmental disorders, and alcohol or substance use disorders were excluded from the study, and written informed consent was obtained from all participants who approved to participate in the study. The study was conducted in accordance with the ethical principles of the Declaration of Helsinki, and ethical approval for the study was granted by the Ethical Commission of the Health Sciences University (Ankara, Turkey).

The participants were administered Brief Psychiatric Rating Scale (BPRS), Clinical Global Impressions Scale (CGI), Scale for the Assessment of Positive and Negative Symptoms (SAPS/SANS), Calgary Depression Scale for Schizophrenia (CDSS), YBOCS, and Global Assessment of Functioning Scale (GAF). The interviewer was a psychiatrist (AK) who was experienced in administering the scales in patients with schizophrenia. The Sociodemographic Data Form included basic demographic information (e.g., age, education, and sex) and some variables related to illness (e.g., illness duration and number of episodes). The BPRS, assessing patient symptoms in multiple ways, is a Likert scale. It is scored between 1 (absent) and 7 (severe) points, and it is used to evaluate the impact of the treatment in psychotic patients through assessing 18 different symptoms such as anxiety, excitement, and depressive mood.[24] The CGI-Severity (CGI-S), assessing the severity of the disorder as a simple rating by the clinician, is a Likert scale. In this scale, the clinician rates the severity of psychopathology of the patient from 1 to 7, and 1 point indicates no psychopathology, whereas 7 points indicate the most extremely ill patients.[25]

The SANS and SAPS were developed by Andreasen.[26] The SANS and SAPS have been widely used to measure the severity of negative and positive symptoms and assessed by the interviewer. The SANS has five subscales and 25 items, and the items are rated from 0 to 5. The subscales of SANS are “affective flattening,” “alogia,” “avolition,” “anhedonia,” and “attention.” The total scores for the subscales and total score for the whole scale are calculated, and it is between 0 and 125.[26] The SAPS has five subscales and 35 items, and the items are rated from 0 to 5. The subscales of SAPS are “hallucinations,” “delusions,” “disorganized behaviors,” “positive formal thought disorder,” and “inappropriate affect.” The total scores for the subscales and the whole scale are calculated, and the total score is between 0 and 170.[26] The CDSS, a 9-item structured interview scale, was designed for the assessment of depressive symptoms, and it has been widely used to differentiate between the negative and positive symptoms of schizophrenia and depressive symptoms. In this scale, the items are rated on a 0–3-point Likert scale, and higher scores indicate severe depressive symptoms within the last 2 weeks in patients with schizophrenia.[27] The Y-BOOCS, a 10-item Likert scale, is used to measure the severity of OCS. The items are rated from 0 to 4, and the total score ranges between 0 (none) and 40 (severe).[23] The GAF, a scale considering impairments in psychological, social, and occupational/school functioning, is used to assign a clinical judgment of an individual's overall functioning level. The GAF scale score ranges from 0 (lower) to 100 (higher functioning) and is included in the DSM-IV.[28]

Statistical analysis

The scales identified above were administered to the patients, and statistical analyses were conducted using the IBM SPSS version 21 (IBM Corp., Armonk, NY, USA).[29] Continuous data were presented as mean and standard deviation, whereas numbers and percentages were calculated for categorical variables. The data of two groups were normally distributed and assessed by the skewness-kurtosis statistics and Q-Q plots. For categorical variables, Chi-square test was used, whereas independent samples t-test was used for continuous variables in order to compare the sociodemographic and clinical characteristics between patients with schizophrenia with and without OCD. All P values were calculated as two sided, and P < 0.05 was considered statistically significant.

RESULTS

Comparison of the sociodemographic and clinical characteristics between patients with and without obsessive-compulsive disorder comorbidity

The sample consisted of 250 schizophrenic patients with a mean age of 39.11 ± 10.67 years. There were 50 patients with an existing OCD comorbidity and 200 patients who did not have an OCD diagnosis for a lifetime. The sociodemographic and clinical characteristics of the two groups and comparison between the two groups are presented in Table 1. Age, gender, marital status, education level, and mean duration of illness were not statistically significantly different between the two groups (P > 0.05). Contrary to sociodemographic variables, most clinical features showed a significant difference depending on the presence of OCD. The results of our study revealed that the onset of schizophrenia was at an earlier age and clozapine use rate was higher in patients presenting OCD comorbidity (P < 0.05). BPRS, CGI-S, and SANS scores were statistically significantly higher in patients with OCD presence (P < 0.05). Furthermore, the GAF scores were higher in patients who did not have an OCD diagnosis for a lifetime, compared to patients with OCD comorbidity (P < 0.05). However, SAPS, CDSS, and schedule for assessing insight (SAI) scores[30] did not show a statistically significant difference depending on the presence of OCD (P > 0.05). The CGI-S and BPRS scores both correlated positively with the YBOCS, SANS, SAPS, and CDSS scores, as well as with the number of hospitalizations and the YBOCS obsessions and compulsions score. However, CGI-S and BPRS scores correlated negatively with the GAF and SAI scores (P < 0.05).

Table 1

Comparison of the sociodemographic and clinical characteristics between patients with obsessive-compulsive disorder and patients without obsessive-compulsive disorder

	Patients with OCD (n=50)	Patients without OCD (n=200)	p	χ2 and F values
Agea	36.80±9.77	39.77±10.79	0.078	F=1.697
Genderb, n (%)
Female	18 (24)	32 (18)	0.300	χ2=1.229
Male	56 (76)	144 (82)
Marital statusb, n (%)
Single or separated	37 (74)	139 (70)	0.606	χ2=0.389
Married	13 (26)	61 (30)
Education levelb, n (%)
Primary school or lower	14 (28)	66 (33)	0.414	χ2=2.859
Middle school	15 (30)	49 (24)
High school	14 (28)	69 (35)
University	7 (14)	16 (8)
Onset agea	21.20±4.68	24.37±7.91	0.007*	F=9.364
Duration of schizophreniaa	14.96±8.75	15.30±7.89	0.793	F=0.017
Number of hospitalizationsa	3.62±2.84	3.04±1.94	0.089	F=2.121
Clozapine use, n (%)	25 (50)	25 (13)	0.000*	χ2=35.156
CGI-1a	4.00±0.67	3.67±0.74	0.004*	F=9.146
SANSa	32.20±6.37	28.81±8.55	0,012*	F=2.667
SAPSa	31.28±7.89	28.76±9.02	0.072	F=0.012
BPRSa	24.86±8.71	20.81±9.35	0.006*	F=0.038
YBOCSa	18.28±2.91	1.19±2.01	0.000*	F=6.818
GAFa	53.20±8.32	56.98±9.44	0.010*	F=0.633
CDSSa	2.44±2.00	1.95±1.80	0.094	F=1.681
SAIa	9.86±1.90	10.34±2.17	0.153	F=2.246

Data; number of cases (%). aIndependent sample t-test; bChi-square test for independence; *P<0.05. BPRS – Brief Psychiatric Rating Scale;[24] CGI – The Clinical Global Impressions Scale;[25] SAPS/SANS – The Scale for the Assessment of Positive and Negative Symptoms;[26] CDSS – The Calgary Depression Scale for Schizophrenia;[27] YBOCS – Yale–Brown Obsessive Compulsive Scale;[23] SAI – The schedule for assessing the three components of insight;[30] GAF – The Global Assessment of Functioning Scale;[28] SD – Standard deviation; OCD – Obsessive-compulsive disorder

Comparison of the sociodemographic and clinical characteristics between patients with preexisting obsessive-compulsive disorder or concurrent obsessive-compulsive disorder onset with psychosis and those manifesting obsessive-compulsive disorder comorbidity during the course of schizophrenia

There were 19 patients presenting OCD features prior to their first psychotic episode (n = 15) or concurrently with psychotic symptoms at the onset of the illness (n = 4), whereas 31 patients manifested OCD comorbidity years after the onset of schizophrenia. Comparison of the patients depending on the onset of OCD is demonstrated in Table 2. The mean duration of OCD was 12.47 ± 8.84 years in patients presenting OCD before or concurrently with psychosis. However, the mean duration of OCD was 5.61 ± 3.69 years in patients manifesting OCD comorbidity during the course of schizophrenia. It was interesting that the average time from OCD diagnosis to the onset of psychosis was about 20 months in patients with preexisting OCD. Age, gender, marital status, education level, onset of schizophrenia, mean duration of schizophrenia, and number of hospitalizations were not statistically significantly different depending on the onset of OCD (P > 0.05). The results of our study revealed that the mean YBOCS score was higher in patients with preexisting OCD or concurrent OCD onset with psychosis, whereas duration of clozapine use was longer in patients who developed OCD during the course of illness (P < 0.05). The BPRS, SAPS, GAF, and the SAI scores did not show a statistically significant difference between the two groups (P > 0.05). However, total SANS and CDSS scores were statistically significantly lower in patients who developed OCD during the illness (P < 0.05).

Table 2

Comparison of the sociodemographic and clinical characteristics between patients presenting obsessive-compulsive disorder before or concurrently with psychosis and patients manifesting obsessive-compulsive disorder during the disorder

	Patients presenting OCD before or concurrently with psychosis (n=19)	Patients manifesting OCD during the disorder (n=31)	p	χ2 and F values
Agea	36.11±9.35	37.23±10.15	0.698	F=0.338
Genderb, n (%)
Female	6 (32)	12 (39)	0.610	χ2=0.260
Male	13 (68)	31 (61)
Marital statusb, n (%)
Single or seperated	4 (21)	9 (29)	0.532	χ2=0.390
Married	15 (79)	22 (71)
Education levelb, n (%)
Primary school or lower	5 (26)	9 (29)	0.135	χ2=5.554
Middle school	3 (16)	10 (32)
High school	6 (32)	8 (26)
University	5 (26)	4 (13)
Onset age of schizophreniaa	21.89±5.70	20.77±3.97	0.417	F=0.815
Duration of schizophreniaa	13.42±8.69	15.90±8.80	0.335	F=0.091
Duration of OCDa	12.47±8.84	5.61±3.69	0.006*	F=8.147
Duration of clozapine usea	1.79±4.14	6.16±4.96	0.002*	F=3.987
Clozapine useb, n (%)	5 (26)	20 (65)	0.009*	χ2=6.876
Number of hospitalizationsa	3.37±1.86	3.77±3.32	0.629	F=0.618
SANSa	34.79±6.41	30.84±6.21	0.036*	F=0.645
SAPSa	32.37±9.12	30.61±7.10	0.450	F=2.120
BPRSa	25.47±8.55	24.48±8.93	0.701	F=0.329
YBOCSa	21.11±4.94	16.55±3.86	0.001*	F=2.070
GAFa	50.53±7.43	54.84±8.51	0.075	F=0.278
CDSSa	3.47±1.90	1.81±1.82	0.003*	F=1.238
SAIa	9.53±1.93	10.06±1.88	0.335	F=0.091

Data; number of cases (%). aIndependent sample t-test; bChi-square test for independence; *P<0.05. BPRS – Brief Psychiatric Rating Scale;[24] SAPS/SANS – The Scale for the Assessment of Positive and Negative Symptoms;[26] CDSS – The Calgary Depression Scale for Schizophrenia;[27] YBOCS – Yale–Brown Obsessive Compulsive Scale;[23] SAI – The schedule for assessing the three components of insight;[30] GAF – The Global Assessment of Functioning Scale;[28] OCD – Obsessive-compulsive disorder; SD – Standard deviation

Treatment of patients with obsessive-compulsive disorder comorbidity

Combination therapy was the most common treatment (n = 30, 60%) and clozapine was the most commonly used antipsychotic in the present study. Clozapine use was less frequent in patients with preexisting OCD and only five of them were under clozapine treatment in that study. There were 17 patients taking amisulpiride, 13 taking aripiprazole, 8 taking paliperidone, 6 taking olanzapine, and 11 patients taking other antipsychotics. Eleven patients on amisulpiride and nine patients on aripiprazole were also taking clozapine. Twenty-two patients were also taking selective serotonin reuptake inhibitors (SSRI) – 10 patients were on sertraline, 8 on fluoxetine, and 4 on escitalopram, and mirtazapine was utilized by four patients in the present study.

DISCUSSION

This cross-sectional study evaluated the clinical correlates of OCD comorbidity in patients with schizophrenia. Previous studies suggest an increased OCD prevalence among patients with schizophrenia compared to the general population. Similar neural pathways are impacted in the etiology of both disorders and that seemed the cause of the high overlap between those disorders. However, patients with and without OCD differed clinically according to past studies. In this study, there were no significant differences in age, gender, and duration of illness between those with and without OCD. Thus, there was no major diversity in the group characteristics causing a clinical bias on the results.

Comparison of the sociodemographic characteristics between patients with and without obsessive-compulsive disorder comorbidity

According to the current literature, there is a lack of consensus on the relationship between sociodemographic characteristics and OCD in schizophrenia.[31] There was no significant relationship between OCD comorbidity and age or gender in previous studies, similar with our study. Some studies reported that schizophrenia patients with OCD had higher education; however, education level was not related with OCD comorbidity in this study.[32] In addition, marital status and socioeconomic status did not show a significant difference between the groups. Contrary to that finding, Owashi et al. found that OCD comorbidity rate was related with lower socioeconomic status in patients with schizophrenia.[33] As a result, it can be concluded that there is no causal relationship between the OCD presence and sociodemographic features of the patients.

Impact of comorbid obsessive-compulsive disorder on the onset of psychosis and schizophrenia symptoms

In contrast to sociodemographic variables, most of the clinical features showed a significant difference between the groups with and without OCD. At first, our study found OCD group patients to have earlier age at the onset of psychotic symptoms. This finding was reported in many previous studies, and earlier onset of psychotic symptoms was related with more severe clinical symptoms and poorer prognosis in schizophrenia according to the current literature. Although it is unclear if OCD presence poses a risk for initiation of psychosis, primary OCD at younger ages may exert an influence on the emergence of schizophrenia.[333435] Future studies should be made to provide a better understanding of the impact of OCD on the onset of schizophrenia.

The BPRS and CGI-S scores were both significantly higher in the OCD group in the present study, and those results were consistent with the findings of many previous studies.[10111236] On the other hand, some studies comparing patients with and without OCD showed no difference in the severity of general psychotic symptoms.[6] The BPRS and CGI-S scores indicate the severity of schizophrenia in a simple way, and they were not determinative scales of the impact of OCD on clinical symptoms in that study. The severity of positive symptoms and hospitalization rate did not show a statistically significant difference between the two groups, similar with the results of a meta-analysis by Cunill et al.[6] Previous studies assessing the relationship between OCD and severity of positive symptoms in patients with schizophrenia have reported contradictory results to the present study.[678] Some studies found no difference in the presence of OCD comorbidity, whereas some others reported more or less severe positive symptoms in patients with OCD comorbidity.[9101112363738] The studies which found more severe positive symptoms in patients with OCD comorbidity reported that the results may be due to the difficulty in the distinction of positive symptoms and OCS and inclusion of heterogenous groups in the studies.[513363738] In this study, positive symptoms were also not determinative in the differentiation of patients with and without OCD.

There was a positive relationship between OCD comorbidity and severity of the negative symptoms in our study. The studies assessing the impact of OCD on negative symptoms have revealed conflicting results, some studies obtained more severe negative symptoms in the OCD group, similar with our study.[121417] However, others found lower negative symptom severity or reported no difference in the severity of negative symptoms with OCD comorbidity.[111519] Severity of the depressive symptoms did not show a significant difference between the groups with and without OCD in the present study. Some studies reported higher severity of depressive symptoms in patients with OCD; however, some studies did not find a significant difference in depressive symptom severity regarding OCD comorbidity.[1314] Thus, there is a lack of consensus on the relationship between depressive symptom severity and OCD presence in schizophrenia.

Impact of comorbid obsessive-compulsive disorder on functioning and insight

Patients with OCD showed poorer functionality compared to patients without OCD, and this is consistent with the findings of previous studies.[39] According to many previous studies, OCD comorbidity was related with poorer psychosocial functionality, lower quality of life, and poorer vocational functioning.[3456] However, some studies suggested that OCD presence was not associated with functioning in schizophrenia.[383940] There was no significant influence of OCD comorbidity on insight level in this study, and previous studies examining the impact of OCD on insight level in schizophrenia reported inconclusive results.[41]

Previous studies suggested that the impact of OCD comorbidity in schizophrenia differs depending on the onset of the comorbidity.[1234] YBOCS, SANS, and CDDS scores were higher in patients presenting OCD before or concurrently with the onset of psychosis, a finding similar with prior studies.[56] It can be proposed that the earlier onset of OCD has a more complex neurobiological basis and is related with more resistant OCD symptoms and poor prognosis. The finding of higher negative and depressive symptoms in patients with OCD preceding or concurrently with psychosis also pointed out a more severe clinical course with earlier onset of OCD in schizophrenia.

Some studies found no relationship between the timing of the onset and severity of negative symptoms, whereas some other studies detected more severe negative symptoms in the preexisting OCD.[3336] Negative symptoms are more resistant to antipsychotic treatment in schizophrenia, and preexisting OCD might cause more persistent negative symptoms. More severe depressive symptoms in those with preexisting OCD were consistent with the findings of previous studies which found higher rate of depression and more severe depressive symptoms with early-onset OCD.[1233940] However, BPRS, SAPS, GAF, and SAI scores did not show a significant difference depending on the onset of OCD symptoms. It can be suggested that both groups had OCD comorbidity, and the comorbidity itself was more determinative on the positive and general psychiatric symptoms compared to the impact of the onset of OCD. As a result, earlier onset of OCD comorbidity, especially preexisting OCD, seems to show different clinical features, and the need for psychosocial therapies to improve negative symptoms is suggested to be higher in those groups. Furthermore, OCD arising during the course of schizophrenia displayed distinct clinical characteristics and seems to require a different clinical approach in treatment.

Impact of clozapine on obsessive-compulsive disorder comorbidity and clinical features in schizophrenia

Clozapine use was associated with OCD comorbidity the present study (P < 0.05). Furthermore, clozapine use was more frequent and the duration of clozapine use was longer in patients manifesting OCD during the disorder compared to those with preexisting OCD (P < 0.05). Both results addressed a relationship between clozapine use and OCD development during the course of schizophrenia and that relationship was also displayed in many clinical studies.[71920] Many studies addressed a significant association between atypical antipsychotic use and manifestation of OCD symptoms.[12] Particularly, antipsychotics with high antiserotonergic effects (i.e., olanzapine and clozapine) were suggested to induce obsessions and compulsions in previous studies.[1213] However, it is still impossible to conclude a certain relationship between OCD development and atypical antipsychotic use as OCD symptoms might appear throughout the lifetime in patients with schizophrenia.[37]

In addition, less severe depressive and negative symptoms were found in patients who developed OCD during the course of schizophrenia. It can be suggested that clinical features differ depending on the timing of OCD (preexisting OCD or OCD onset during schizophrenia). Furthermore, less severe depressive symptoms could be provided by the impact of clozapine as clozapine was found to improve depressive symptoms in some studies.[2021]

Even though OCD is a common comorbidity in schizophrenia, there is a paucity of research on its treatment. Combination therapy was the most common treatment (n = 30, 60%), and clozapine was the most commonly used antipsychotic in our study. This result might be due to the clinical severity of the disorder in the patients included. Clozapine was better at improving psychotic symptoms in patients with resisting symptoms according to most clinical studies, and that finding possibly increased clozapine use. In the present study, clozapine use was more frequent in patients who developed OCD subsequently compared to those with preexisting OCD. Although those with preexisting OCD had more severe clinical symptoms, clozapine was less preferred in that group and only five of them were under clozapine treatment. This may be due to the arguments supporting the induction of OCD symptoms by clozapine.[8] There were 17 patients taking amisulpiride, 13 taking aripiprazole, 8 taking paliperidone, 6 taking olanzapine, and 11 patients taking other antipsychotics. Drugs with less antiserotonergic profile seem to be better in improvement of both psychotic and OCD symptoms in the treatment of those with OCD, and amisulpiride and aripiprazole were possibly utilized for that purpose in our study.[42] The finding that 11 patients on amisulpiride and nine patients on aripiprazole were also taking clozapine supported the explanation above.

Twenty-two patients were also taking SSRI – 10 were on sertraline, 8 on fluoxetine, and 4 on escitalopram, and mirtazapine was used by four patients in the present study. SSRIs were found to be useful in some cases for the treatment of OCD symptoms in schizophrenia, and they can be considered in combination with antipsychotics.[38] There is no much good-quality evidence about any particular suggestions for treatment, and there is limited evidence on SSRI, aripiprazole, mirtazapine, and cognitive behavioral therapy until now. Those options could be utilized more frequently to treat persistent OCD in schizophrenia.

Our study has several limitations. First, as a cross-sectional study, it does not enable causal associations to be drawn between the factors studied; the results should be confirmed in prospective follow-up studies. In addition, OCD features were not evaluated on a dimensional approach and impact of the treatment on OCD features was not assessed. In addition, the scales were administered by a single author, and cognitive functions were not assessed. Determining the dimensions of OCD in schizophrenia and assessing the impact of the treatment on OCD symptoms in wide-centered studies may increase our understanding of the issue.

CONCLUSIONS

There is increasing awareness of the need to address the impact of OCD on the clinical characteristics of schizophrenia in recent years. OCD comorbidity should be evaluated in all patients with schizophrenia as the presence of OCD brings about distinct clinical features in schizophrenia. OCD comorbidity is usually related with lower functionality and poor course; thus, psychotherapeutic interventions and psychosocial programs should be recommended in those patients. Prospective studies regarding how to improve OCS and functionality of the patient while managing psychotic features are needed.

Financial support and sponsorship

No financial support was received from any institution. The fee required for the study was paid by the authors.

Conflicts of interest

There are no conflicts of interest.