Psychopathology and cognition in divergent functional outcomes in schizophrenia

Cognitive performance rather than symptoms, especially positive symptoms, is regarded as the primary predictor of functional outcome in schizophrenia. However, contradictory evidence exists and many studies fail to sample from the extremes of outcome measures. This study tested whether the differential importance assigned to symptoms and cognitive impairment is supportable in patients with high and low levels of community independence. Schizophrenia patients with highly unfavorable (n=24) and highly favorable (n=28) functional outcomes as defined by community support requirements were studied. Standard cognitive and psychopathology measures were analyzed using independent groups comparisons and outcome prediction with logistic regression methods. Symptom severity and cognitive data separately accounted for significant amounts of variance in community independence. Positive as well as negative symptoms, non-psychotic psychopathology and cognition generated large effect sizes between highly unfavorable and favorable outcome groups. The conditional validity of both overall psychopathology and positive symptoms was significant over and above the contribution of cognition to outcome prediction. Results suggest researchers may have underestimated the role of psychopathology in general and positive symptoms in particular as potential determinants of functional status in schizophrenia.