Durability and mechanism of effects of cognitive enhancement therapy

This study sought to determine whether previously reported effects of cognitive enhancement therapy (CET) are maintained one year after treatment. CET is a developmental, small-group approach to the remediation of neurocognitive and social-cognitive deficits among persons with schizophrenia. A mechanism of action that might explain the effects of CET was also sought.

After a study in which 121 participants with schizophrenia or schizoaffective disorder were randomly assigned to CET (N=67) or an enriched supportive therapy (EST) (N=54) for a two-year period, 106 patients who completed treatment underwent behavioral and neuropsychological assessments one year later. Data were analyzed by linear trend analysis. Mechanisms of action were explored with a mediator analytic strategy.

Significant improvement favoring CET continued through the follow-up year on composite measures of processing speed, cognitive style, social cognition, and social adjustment. The difference between CET and EST on the neurocognition composite measure was not maintained because the stress-regulating effects of treatment appeared to lead to improved neurocognitive performance in both groups. Early improvement in processing speed was a strong (partial) mediator of long-term CET effects on social cognition and social adjustment. To a lesser extent, early improvement in neurocognition partially mediated changes in cognitive style (impoverished, disorganized, or rigid) in the CET group but had little influence on social adjustment or social cognition in the CET group.

Most effects of the highly efficacious CET were sustained one year after treatment. Early improvement in processing speed (and perhaps other unassessed aspects of attention) seems to be the principal mediator of CET effects.