Neuropsychological profile and treatment-related features among patients with comorbidity between schizophrenia spectrum disorder and obsessive-compulsive disorder: Is there evidence for a "schizo-obsessive" subtype?

Epidemiological studies have found that obsessive-compulsive disorder (OCD) is estimated to occur in 12% of patients with schizophrenia. Whether this "schizo-obsessive" subgroup may be posited as a clinical entity with a distinct neuropsychological profile and treatment-related features remains unclear. A sample of 30 patients who met DSM-IV criteria for both schizophrenia/schizoaffective disorder and OCD was compared with 30 OCD subjects and with 37 patients with schizophrenia/schizoaffective disorder. Neuropsychological domains were measured by the Wechsler Adult Intelligence Scale - Third Edition (WAIS-III), the Trail Making Test (TMT), and the verbal fluency test (FAS). Treatment-related variables were assessed with the Clinical Global Improvement scale (CGI), the Drug Attitude Inventory (DAI), and dosage/type of antipsychotic medications. One-way analysis of variance revealed statistically significant differences among the three groups in "working memory," "block design," "semantic fluency," TMT-A, and TMT-B. However, the Bonferroni correction showed no statistical differences between both psychotic groups. In addition, there were no significant differences among the three groups in the CGI and DAI, although "schizo-obsessive" patients tended to display slightly higher scores on these variables than the other groups. Overall, these findings do not support the hypothesis that comorbidity between schizophrenia spectrum disorders and OCD may reflect a distinct clinical entity. However, further research with larger sample sizes and a more comprehensive clinical assessment are needed. Our findings also underscore the fact that divergences among assessment instruments, as well as confounding variables, may influence results on neuropsychological domains.