Prevalence of cannabis use in psychosis-affected youth: Insights from an Ontario-based early intervention cohort

Cannabis use has long been linked to the emergence and worsening of psychotic disorders, particularly among adolescents and young adults. This study aimed to determine the prevalence of cannabis use and its psychiatric associations in youth and young adults enrolled in an Early Psychosis Intervention (EPI) program in Southeast Ontario. A retrospective cross-sectional analysis was conducted on 116 individuals aged 14-35 who were consecutively enrolled in the EPI program between 2016 and 2019. Data on demographic characteristics, psychiatric diagnoses, and self-reported cannabis use were extracted from clinical records. Statistical analyses were performed to examine associations between cannabis use and variables such as age, gender, educational background, and psychiatric comorbidities. Cannabis use was self-reported by 82.8% of participants. The majority of users were male, and use was most prevalent among individuals aged 18-25. A significant association was found between cannabis use and diagnoses of substance-induced psychosis (p < 0.001). Lower levels of formal education were more frequent among cannabis users compared to non-users (p = 0.004).This study identified a strikingly high rate of cannabis use among youth engaged in early psychosis care, particularly among males and young adults in their early twenties. The findings underscore the importance of routine screening, targeted psychoeducation, and harm reduction strategies within EPI programs. Given the strong association with substance-induced psychosis, early identification and integrated treatment approaches are essential to improve long-term outcomes in this population.