Relationship of cognition and psychopathology to functional impairment in schizophrenia

This study evaluated the association of neurocognition and symptoms with measures of social and occupational functioning in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE).

CATIE was an 18-month study of individuals with schizophrenia. Symptoms of 1,386 patients were measured with the positive syndrome scale of the Positive and Negative Syndrome Scale (PANSS) and a PANSS negative symptom scale that eliminated items that most overlap with measures of community functioning or neurocognition. The Heinrichs-Carpenter Quality of Life Scale, which a rater completes on the basis of the patient's self-report, and recent employment were used to assess community functioning. Hierarchical regression analyses and mixed models tested the association of neurocognition and symptoms with social/occupational functioning as well as changes in these measures during treatment.

Both symptoms and neurocognition were associated with quality of life in bivariate correlation analyses. Symptoms contributed more to the incremental explained variance in quality of life than did neurocognitive functioning, but both kinds of measures were significantly related to quality of life. In an analysis including only the positive syndrome scale, the increased explained variance in quality of life was about equal to that associated with neurocognition. Neurocognition and both symptom measures were independently associated with quality of life in the cross-sectional mixed-model analysis. Changes in neurocognition and both symptom measures during treatment were also significantly associated with change in the quality of life.

Both psychotic symptoms and neurocognitive deficits appear to contribute independently to decreased quality of life in schizophrenia.