Cognitive deficits in schizophrenia. Prediction of symptom change for participators in work rehabilitation

While recent studies have found that most patients with schizophrenia who participate in work rehabilitation experience symptom improvement, there appears to be a subgroup of patients whose symptoms remain stable or even worsen. The present study explores the hypothesis that cognitive impairment is one factor which reduces the clinical effectiveness of rehabilitation and accounts for a lack of improvement in some patients. To explore this question, performance on two neuropsychological tests was used to predict improvement on six symptom dimensions for 59 subjects who completed 5 months of work in a rehabilitation program. Discriminant function analyses indicated that quadratic combinations of standardized scores on the Wisconsin Card Sorting Test and thought disorder scores from the Gorham Proverbs Test could correctly classify 83% of subjects as improved or unimproved on a total symptom measure, and between 84% and 100% of subjects as improved or unimproved on various symptom dimensions, with greater levels of cognitive impairments at intake predicting no symptom improvement. Implications for the potential role of cognitive remediation in rehabilitation are discussed.