[Comorbidity between obsessive-compulsive disorder and schizophrenia: prevalence, explanatory theories, and nosological status].

This theoretical study reviews the main findings and research on comorbidity between obsessive-compulsive disorder (OCD) and schizophrenia. On the one hand, it is argued that high prevalence of comorbidity implies common risk factors (neuroanatomical and neuropsychological correlates) and a causal relationship between these mental illnesses, OCD usually preceding schizophrenia. On the other hand, independent nosological status of this “comorbidity” is supported on the basis of several external criteria (negative symptomatology, depressed mood, psychosocial impairment, neurobiological and neuropsychological correlates), which distinguish this mixed clinical entity from OCD and schizophrenia separately. These conclusions are discussed, considering the lack of recognition of “schizo-obsessive disorder” within the current diagnosis reference manuals.