Comparison of neurocognitive domains in patients with schizophrenia with and without co-morbid obsessive compulsive disorder
Introduction
Schizophrenia is often associated with many co-morbid psychiatric disorders which further adds on to its severity and poses several challenges in its management (Buckley et al., 2009).Studies have reported that about 12% and 30% of patients with schizophrenia have obsessive–compulsive symptoms (OCS) and obsessive compulsive disorder (OCD) respectively (deHaan et al., 2013; Swets et al., 2014).The effect and impact of OCD on the clinical profile of schizophrenia has been the subject of several recent studies yielding inconclusive results (Cunill et al., 2009). Apart from causing significant clinical impairment and poor social functioning, OCD in schizophrenia has also been shown to possibly have negative impact on cognitive deficits (Frías et al., 2014; Lysaker et al., 2002; Schirmbeck et al., 2013; Whitney et al., 2004). However, efforts to differentiate schizophrenia patients with and without co-occurring OCD in terms of cognitive deficits have revealed conflicting results (Frías et al., 2014).
Studies have compared patients of schizophrenia with co-morbid OCS (Berman et al., 1998; Reznik et al., 2005) or co-morbid OCD (Tumkaya et al., 2009; Whitney et al., 2004), with those without co-morbid OCS/OCD. In either case, in general there is some evidence to suggest that patients with comorbid OCS or OCD, have larger deficits in the domains of executive functioning, cognitive flexibility and visual memory (Berman et al., 1998). Further, some of the studies had found correlations between severity of OCD with higher level of delayed visual memory deficits, executive functioning deficits and decreased cognitive flexibility (Schirmbeck et al., 2013). However, some studies have not found any significant difference between patients with and without OCS/OCD (Tumkaya et al., 2009; Whitney et al., 2004), whereas others suggest that presence of OCD may be associated with better performance on some of the cognitive domains (Borkowska et al., 2003; Kumbhani et al., 2010; Lee et al., 2009). The inconsistencies in the results of these studies can be attributed to the heterogeneity within the clinical samples, the type of neurocognitive tests used for assessment and small sample sizes. Hence, there is a need to evaluate this area further. In recent times, the relationship of OCS/OCD with schizophrenia is understood in different ways and OCD in schizophrenia is understood to have 4 different kind of associations with symptoms of schizophrenia, i.e., OCS/OCD occurring during the prodromal phase of schizophrenia, OCS/OCD occurring concurrently with symptoms of schizophrenia, OCS/OCD occurring during the residual phase of schizophrenia and antipsychotic associated OCS/OCD or de novo OCD (Schirmbeck and Zink, 2013). However, studies which have evaluated neurocognition have not tried to segregate patients with comorbid OCD into those with OCD as part of schizophrenia and OCD induced by antipsychotic medications (de novo).
In view of the inconsistencies in literature, as per null hypothesis, we hypothesized that patients of schizophrenia with and without comorbid OCD will not differ on the various neurocognitive domains. Further, it was hypothesized that there would be no significant difference in the neurocognitive functions among patients with OCD as part of illness and OCD induced by antipsychotic medications (de novo). Accordingly, the present study aimed to compare the neurocognitive functions of patients with schizophrenia with and without co-morbid OCD. An attempt was made to evaluate the relationship between neurocognitive functions and severity of OCD. Additionally, an attempt was made to compare the neurocognitive profile of patients with comorbid OCD and antipsychotic induced OCD/de novo OCD.
Section snippets
Materials and methods
This cross-sectional study was conducted at the psychiatry outpatient and inpatient services of a tertiary care hospital in North India. The study was approved by the Ethics Committee of the Institute and the study participants were recruited after obtaining written informed consent.
The study sample comprised of 2 groups of patients. Group 1 included 40 patients with schizophrenia with co-morbid OCD and group-2 comprised of 39 patients with schizophrenia without co-morbid OCD. All subjects and
Results
The study included 79 subjects of schizophrenia of which 40 subjects were in group I (schizophrenia with OCD) and 39 subjects in the group II (schizophrenia without OCD). Further, when the relationship of OCD with antipsychotic use was evaluated, 26 subjects had OCD as an intrinsic part of the illness (Group Ia = 26) and 14 patients had development of OCD after the starting of antipsychotics i.e., had antipsychotic induced OCD/de novo OCD (Group Ib = 14).The demographic and clinical profile of
Discussion
The primary aim of the study was to compare the neurocognitive functioning of patients with schizophrenia with and without comorbid OCD. Present study reveals that compared to those without comorbid OCD, patients of schizophrenia with OCD have poor processing speed, poor verbal fluency, low cognitive flexibility and poor executive functioning. These findings provide credence to earlier studies which have noted negative influence of comorbid OCD on patients with schizophrenia (Cunill et al., 2013
Source of funding
None.
Contributors
Empty Cell SG SS RN Concept √ √ Collection of data √ √ Analysis of data √ √ Review of literature √ √ Drafting of manuscript √ √ Final approval of manuscript √ √ √
Conflict of Interest
None.
Acknowledgement
None.
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