Cognitive functioning in children and adolescents in their first episode of psychosis: differences between previous cannabis users and nonusers.
This study compared psychiatric outpatients who were never, former, and current substance abusers on psychiatric, social, and cognitive functioning. Fifty-six outpatients with schizophrenia spectrum and bipolar disorders volunteered to complete diagnostic and social role function interviews, self-report inventories, and neuropsychological tests. Multinomial logit regression analyses indicated that current and former abusers reported greater subjective feelings of distress than those who never abused. Contrary to expectations, however, both groups of substance abusers performed better on nonverbal cognitive tests compared with those who never abused. Differences in social functioning were also observed: former abusers demonstrated better instrumental role functioning than those who never abused. This pattern of findings challenges assumptions about additive effects of comorbid disorders on cognitive and social functioning.