Prevalence of Cannabis Use among Youth and Young Adults Attending an Early Psychosis Intervention Program in Ontario, Canada

Background: Cannabis use is associated with an increased risk of developing psychosis in youth and younger adults (YAYA). However, differences in accessibility and consumption patterns may influence prevalence rates in different populations. This study aimed to investigate the prevalence of cannabis use and its associations among young adults attending an Early Psychosis Intervention (EPI) program in Southeast Ontario. Methods: A cross-sectional study of 116 youth and young adults enrolled in the Southeast Ontario EPI program between 2016 and 2019. Demographic characteristics and psychiatric diagnoses were identified from the clinical records. Statistical analyses were performed to examine the prevalence of cannabis use, its correlation and association with alcohol and other substance use, and the association with psychotic disorders. Results: The study revealed a very high prevalence of cannabis use among YAYA attending the EPI program, with 82.8% self-reporting cannabis use. Males showed a higher prevalence of cannabis use (71.9% than females 28.1%), with a male-to-female ratio of 2.6:1. Significant associations were found between cannabis use and psychiatric disorders, including psychosis and substance-induced psychotic disorder (SIP) (P-value< 0.05). Conclusion: This study highlights the need for the screening and recognition of harmful cannabis use with specific and targeted interventions to reduce the potential serious mental health effects in youth and young adults presenting with early psychosis. Early intervention incorporating motivational enhancement, and lower-risk cannabis use alongside psychological and pharmacological therapies serve to reduce the harmful impact of cannabis, shortening the duration of untreated psychosis and supporting functional recovery.