Pathways to functional outcomes in schizophrenia: The role of premorbid functioning, negative symptoms and intelligence

Background: Social and intellectual premorbid functioning are generally estimated retrospectively, and related to clinical or hospitalization outcomes in schizophrenia. Yet the relationship between premorbid functioning assessed prior to psychiatric hospitalization and postmorbid functional outcomes has not been examined. Objectives: To test competing models of the relationship between (a) functional outcomes with (b) premorbid functioning assessed on nationally administered tests prior to psychiatric hospitalization, postmorbid intellectual functioning and symptomatology using a historical prospective design. Methods: Ninety one inpatient and outpatient males with schizophrenia or schizoaffective disorder, aged 19 to 35, were examined using the Positive and Negative Syndrome Scale, the WAIS-III and Strauss and Carpenter social and occupational functional outcome scale. Premorbid intelligence and social functioning data were obtained from national standardized tests administered during high school prior to first hospitalization for schizophrenia. Results: Path modeling showed that premorbid intelligence and behavioral functioning directly predicted postmorbid IQ and negative symptoms, and indirectly predicted postmorbid social and occupational functioning via negative symptoms. Item level analysis indicated that better social and occupational outcomes occurred in a group with few negative symptoms. Conclusions: Premorbid functioning, postmorbid IQ and negative symptoms are related, yet the relationship between premorbid functioning and postmorbid functional outcomes appears to be mediated by postmorbid negative symptoms.