Cannabis use and cognitive functions in at-risk mental state and first episode psychosis

BACKGROUND: Meta-analyses suggest that schizophrenia patients with a history of cannabis use have less impaired cognitive functioning compared to patients without cannabis use. AIMS: The objective of this study was to assess the association between recency and frequency of cannabis use and cognitive functioning in at-risk mental state for psychosis (ARMS) and first episode psychosis (FEP) individuals. METHODS: One hundred thirty-six participants completed a cognitive test battery and were assessed for current and past cannabis use. Analyses of covariance models were applied to evaluate the main effects of cannabis use and patient group (ARMS vs. FEP) as well as their interactions on cognitive functioning. RESULTS: No differences were observed in cognitive performance between current, former, and never users, and there were no significant interactions between cannabis use and patient group. Furthermore, within the group of current cannabis users, the frequency of cannabis use was not significantly associated with cognitive functioning. CONCLUSION: The results of the present study do not support the notion that FEP patients and ARMS individuals with a history of cannabis use have less impaired cognitive functioning compared to those without cannabis use.