The effect of obsessive-compulsive symptomatology on executive functions in schizophrenia: a systematic review and meta-analysis.

The presence of obsessive-compulsive symptoms (OCS) and obsessive-compulsive disorder (OCD) is frequent in patients with schizophrenia and has been associated with greater functional impairment. The impact of these features on cognitive function is unclear. In this article, we performed a systematic review and meta-analysis to assess the effect of OCS/OCD on executive functions in schizophrenia patients. Results indicate that schizophrenia patients with OCS/OCD were more impaired in abstract thinking than schizophrenia patients without OCS/OCD. This finding provides support to the double jeopardy hypothesis and may partially explain the greater functional impairment shown in schizo-obsessive patients compared to those with schizophrenia. Inconsistent results were found for set-shifting, cognitive flexibility, cognitive inhibition and verbal fluency, as indicated by the high statistical heterogeneity found. Potential sources of heterogeneity such as definition of OCS/OCD, age of onset, severity of negative symptoms and premorbid intelligence were planned to be explored but there was an insufficient number of studies to perform these analyses. Our findings highlight the complexity of the relationship between OCS/OCD and schizophrenia and warrant further investigation of the cognitive function of schizo-obsessive patients.