Cognitive enhancement therapy for schizophrenia: effects of a 2-year randomized trial on cognition and behavior

Abstract

Background: Deficits in social cognition and neurocognition are believed to underlie schizophrenia disability. Attempts at rehabilitation have had circumscribed effects on cognition, without concurrent improvement in broad aspects of behavior and adjustment.

Objective: To determine the differential effects of cognitive enhancement therapy (a recovery-phase intervention) on cognition and behavior compared with state-of-the-art enriched supportive therapy.

Design: A 2-year, randomized controlled trial with neuropsychological and behavioral assessments completed at baseline and at 12 and 24 months.

Setting: An outpatient research clinic housed in a medical center's comprehensive care service for patients with severe mental illness.

Patients: A total of 121 symptomatically stable, non-substance-abusing but cognitively disabled and chronically ill patients with schizophrenia or schizoaffective disorder.

Interventions: Cognitive enhancement therapy is a multidimensional, developmental approach that integrates computer-assisted training in neurocognition with social cognitive group exercises. Enriched supportive therapy fosters illness management through applied coping strategies and education.

Main outcome measures: Six highly reliable summary measures--Processing Speed, Neurocognition, Cognitive Style, Social Cognition, Social Adjustment and Symptoms--were tested using analysis of covariance and linear trend analysis.

Results: At 12 months, robust cognitive enhancement therapy effects were observed on the Neurocognition and Processing Speed composites (P<.003), with marginal effects observed on the behavioral composites. By 24 months, differential cognitive enhancement therapy effects were again observed for the 2 neuropsychological composites and for Cognitive Style (P=.001), Social Cognition (P=.001), and Social Adjustment (P=.01). As expected, no differences were observed on the residual Symptoms composite. Effects were unrelated to the type of antipsychotic medication received. Enriched supportive therapy also demonstrated statistically significant within-group effect sizes, suggesting that supportive psychotherapy can also have positive, although more modest, effects on cognitive deficits.

Conclusion: Many cognitive deficits and related behaviors of patients with stable schizophrenia are improved when sufficient exposure to relevant rehabilitation is provided.