Suspiciousness as a specific risk factor for major depressive episodes in schizophrenia

Objective: Serious depression is a common and important complication of schizophrenia. In a prospective, population-based study, we tested the hypothesis that suspiciousness increases the risk for the later development of depression in schizophrenia. Method: Data came from the Epidemiological Catchment Area (ECA) study. Baseline clinical and demographic features were used to predict the onset of new episodes of depression at 1 year follow-up. As ECA diagnoses were based on lay interviews, which may have low sensitivity compared with clinical diagnoses, two overlapping groups of putative schizophrenia patients were defined. Results: Suspiciousness was associated with an increased risk of new episodes of depression in both patient groups, after accounting for demographic variables. There was no association between an increased risk of depression and either disorganization or hallucinations and delusions. Conclusions: Suspiciousness appears to be a specific risk factor for depression in psychotic groups. Interventions that decrease suspiciousness, or mitigate its isolating effects, might decrease the risk of serious depression and suicide.