The relationship of neuropsychological abilities to specific domains of functional capacity in older schizophrenia patients

Background: This study sought to determine the relative importance of cognitive measures in predicting various domains of everyday functional capacity in older outpatients with schizophrenia. Methods: Ninety-three psychiatry outpatients with diagnoses of schizophrenia and schizoaffective disorders underwent a comprehensive neuropsychiatric evaluation, including neuropsychological testing and clinical ratings of psychopathology. Functional capacity was assessed with the Direct Assessment of Functional Status, a performance measure of basic and instrumental activities of daily living (ADLs/IADLs). Results: Neuropsychological performance significantly predicted most ADLs/IADLs measured, except simple eating behaviors, time orientation, and grooming. Lower educational level and negative symptoms also were associated with worse functional capacity, whereas positive symptoms and depressed mood were not. Measures of cognitive functioning accounted for more variance in functional capacity than did psychiatric ratings of symptoms, and multiple regression analyses demonstrated that neuropsychological performance was predictive of functional capacity, over and above clinical symptoms. No specific cognitive domains were differentially predictive of specific domains of functional capacity. Conclusions: Neurocognitive abilities were more predictive of functional capacity than level of clinical symptoms; however, these abilities were not specific predictors of functioning. This is consistent with findings of relatively generalized, intercorrelated cognitive impairment in schizophrenia and multiply determined domains of everyday functioning.