Comparison of neurocognitive domains in patients with schizophrenia with and without co-morbid obsessive compulsive disorder

Abstract

Background: Neurocognitive deficits have been well documented in patients with schizophrenia. Research has shown that a significant proportion of patients with schizophrenia have co-morbid obsessive-compulsive symptoms/disorder (OCS/OCD). However, the impact of OCS/OCD on various neurocognitive domains in patients with schizophrenia is less understood.

Methods: 40 patients with schizophrenia and comorbid OCD (Group-I) were matched with 39 patients with schizophrenia without OCD (Group-II) and were assessed on Trail making test A and B (TMT-A/B), Controlled Oral Word Association test (COWA), Stroop test and Tower of London (TOL). Psychopathology was assessed by using Positive and Negative syndrome Scale (PANSS). Severity of OCD was assessed by using Yale-Brown Obsessive Compulsive Scale (Y-BOCS).

Results: Compared to patients without comorbid OCD, those with comorbid OCD had more severe cognitive deficits, with medium to large effect sizes. Significant differences were noted in the domains of processing speed (TMT-A; p = 0.018), verbal fluency (COWA; p < 0.001), cognitive flexibility (TMT-B; p = 0.006) and in executive functioning (TOL-2 moves, 3 moves and 4 moves problems). There was significant associations in Group I Y-BOCS total score with the domains of verbal fluency (perseveration words, p = 0.006, variant words, p = 0.036), cognitive processing and selective attention (Stroop score, p = 0.04) and executive functioning (significance noted in 2 moves problems only).

Conclusions: Co-morbid OCD in schizophrenia is associated with more neurocognitive impairment as compared with schizophrenia without OCD. Accordingly, more intensive interventions must be carried out to address the neurocognitive deficits in patients of schizophrenia with OCD.

Keywords: Neuro-cognitive deficits; Obsessive-compulsive disorder; Schizophrenia.