Impact of intellectual status on response to cognitive task training in patients with schizophrenia

Cognitive remediation is a promising rehabilitation procedure for people with schizophrenia, but very little is known about who can benefit. In the current analyses, we examined the role of pre-morbid and morbid intellectual function in predicting response to cognitive remediation in a sample of 152 patients diagnosed with schizophrenia or schizoaffective disorder. They were participants in a trial of work therapy and cognitive remediation and had been randomized to receive either Neurocognitive Enhancement Therapy with Work Therapy (NET + WT) or Work Therapy only (WT only). For the current analyses, patients were divided into three intellectual subgroups based on their pattern of premorbid and morbid deficits (preserved intelligence, compromised intelligence, and deteriorated intelligence), and their cognitive remediation outcomes were examined. Cognitive remediation response was measured in two ways: normalization of performance on a computerized training task, and pre-post neuropsychological test performance. Subjects in NET + WT showed greater improvement in cognition than those in WT only, but response differed by intellectual group. For patients in the compromised group, those in NET + WT showed a significantly higher proportion of task normalization than those in the WT only condition, but no such differences were found with the preserved and deteriorated intellectual groups. For patients in the preserved and deteriorated intellectual groups, those in the NET + WT condition showed significantly greater improvement in the analysis of pre-post neuropsychological test performance, but this difference was not found in the compromised intellectual group. These findings suggest that the compromised intellectual group, which had the lowest frequency of normal performers at intake, benefited from NET by achieving dramatic increases in normalization, but that they had difficulty in generalizing these gains to untrained tasks. Those in the preserved and deteriorated intellectual groups were more successful in generalizing their training.