Adolescent Initiation of Cannabis Use and Early-Onset Psychosis

ABSTRACT

Background: It is important to evaluate the impact of cannabis use on onset and course of psychotic illness, as the increasing number of novice cannabis users may translate into a greater public health burden. This study aims to examine the relationship between adolescent onset of regular marijuana use and age of onset of prodromal symptoms, or first episode psychosis, and the manifestation of psychotic symptoms in those adolescents who use cannabis regularly. Methods: A review was conducted of the current literature for youth who initiated cannabis use prior to the age of 18 and experienced psychotic symptoms at, or prior to, the age of 25. Seventeen studies met eligibility criteria and were included in this review. Results: The current weight of evidence supports the hypothesis that early initiation of cannabis use increases the risk of early onset psychotic disorder, especially for those with a preexisting vulnerability and who have greater severity of use. There is also a dose-response association between cannabis use and symptoms, such that those who use more tend to experience greater number and severity of prodromal and diagnostic psychotic symptoms. Those with early-onset psychotic disorder and comorbid cannabis use show a poorer course of illness in regards to psychotic symptoms, treatment, and functional outcomes. However, those with early initiation of cannabis use appear to show a higher level of social functioning than non-cannabis users. Conclusions: Adolescent initiation of cannabis use is associated, in a dose-dependent fashion, with emergence and severity of psychotic symptoms and functional impairment such that those who initiate use earlier and use at higher frequencies demonstrate poorer illness and treatment outcomes. These associations appear more robust for adolescents at high risk for developing a psychotic disorder.

Keywords:

• Adolescent
• cannabis
• early-onset
• psychosis

AUTHOR CONTRIBUTIONS

Dr. Bagot completed the initial literature search for data collection, drafted the initial and subsequent versions of the manuscript, including designing and formatting, and revised and approved the final manuscript as submitted. Dr. Milin provided additional articles to include in the review (beyond the initial literature search) in regards to data collection as well as provided analyses of those and the original articles, edited each draft of the manuscript, and approved the final manuscript. Dr. Kaminer conceptualized the review, aided in the selection and analysis of included articles, edited each draft of the manuscript, and approved the final manuscript with revisions as submitted.

Funding

Dr. Bagot reports no financial support or conflicts of interest. Dr. Kaminer receives financial support from the National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism and royalties for books from Hazelden, Routledge, and American Psychiatric Publishing, Inc. (APPI). Dr. Milin receives financial support from the Institute of Mental Health Research, University of Ottawa, and has received speaker honorarium from Bristol-Myers Squibb Canada, American Academy of Child and Adolescent Psychiatry, and American Academy of Addiction Psychiatry.There were no funding sources for conducting this research or manuscript preparation.