Schizophrenia: lifetime co-morbidity in a community sample.

Twenty persons with schizophrenia were identified in a community sample of 2144 adult household residents interviewed by trained lay interviewers using the Diagnostic Interview Schedule. The hierarchy-free lifetime prevalence for a variety of psychiatric disorders is compared in those with and without schizophrenia. Those with schizophrenia were found to have increased chances of having other disorders, all except one having had at least one other disorder. Major depressive episodes, obsessive compulsive disorder, phobia, alcohol abuse/dependence and drug abuse/dependence, each occurred in over half of the schizophrenics, and panic disorder, antisocial personality, and mania were each found in one sixth to one quarter of the schizophrenics. Although current diagnostic systems generally lack an empirical basis for hierarchies, the practical significance of co-morbidity must be determined from outcome studies, familial morbid risk data and possible differential effects of treatments.