The relationship between cannabis use and cognition in people diagnosed with first-episode psychosis.

Among 89 people diagnosed with first-episode psychosis, 61 were lifetime cannabis users (at least three times per week for four weeks) and 28 were non-users. Cannabis users were more likely to be male and had more positive symptoms, while non-users had more negative symptoms. No differences were found between the groups on tests of verbal memory, verbal fluency, and attention. The authors conclude that cannabis use showed no association with cognitive impairments in this population.

Study at a glance

Abstract

Cannabis use is highly prevalent among young people diagnosed with first-episode psychosis (FEP), however, its impact on cognition is still unclear. The aim of the present study was to examine the association of cannabis use with cognition in people diagnosed with FEP. We extended previous research findings by operationalising the comorbid cannabis use, considering recency of cannabis use and use of other illicit substances and including people with a broad spectrum of psychotic diagnoses. A total of 89 people diagnosed with FEP were interviewed about their history of substance use and completed a cognitive test battery assessing verbal memory, verbal fluency and attention. Sixty-one participants were lifetime cannabis users (CU; ≥three times per week for ≥four weeks; 68.5%) and 28 were cannabis non-users (CNU; 31.5%). CU were significantly more likely to be male and exhibited significantly more positive symptoms than CNU. In contrast, CNU displayed significantly more negative symptoms than CU. There were no differences between CU and CNU on neurocognitive tasks of verbal memory, verbal fluency and attention. In conclusion, there was no indication that cannabis use was associated with cognitive impairments in people diagnosed with FEP.