It has almost always been assumed that cannabis consumption among adolescents leads to the onset and development of psychoses. However, there might be other causal explanations for the association between cannabis use and the risk for psychosis, for instance, susceptibility to both cannabis use and suffering from psychopathology or in the sense of self-medication from the distress arising from psychotic symptomatology.
The adolescents involved are questioned in the research as to whether their use of cannabis will lead to changes in the psychosis spectrum symptoms, indicate shared vulnerability to both cannabis use and risk for psychosis, or self-medication for the symptoms: for this, research published in JAMA Psychiatry.
Test 3 hypotheses that could assume cannabis and risk for psychosis or associations modeled for psychosis spectrum symptom trajectory before and after cannabis exposure during developing adolescence (approximately 10-15 years) and this is a cohort study that collected data over 5 waves in 4 years of follow-up from the Adolescent Brain Cognitive Development (ABCD) study. It is an ongoing large-scale cohort study that started in June 2016 and involves brain development, and health outcomes of American children. It is a prospective study with panel data from a total of 21 research sites. Data were collected from 11,868 adolescents who were aged 9 and 10 by the baseline. There are three subjects dropped from this analysis for missing data. Data analysis runs from September 2023 to July 2024.
The mean (SD) age among 11,858 participants in wave 1 was 9.5 (0.5) years; 6,182 (52%) were male. Supporting the shared vulnerability hypothesis, young people who report using cannabis at any time during the study period also indicated increased severity in psychosis spectrum symptomatology (B, 0.86; 95% CI, 0.68-1.04) and higher distress (B, 1.17; 95% CI, 0.96-1.39) due to symptomatology compared with never users. Time to cannabis initiation summed the increase in the number of psychosis spectrum symptoms (B, 0.16; 95% CI, 0.12-0.20) and increased distress (B, 0.23; 95% CI, 0.21-0.26) experienced around symptoms associated with psychosis. Mixed evidence was discovered to support an increase in symptoms after the initiation of cannabis use (i.e., contributing risk hypothesis).
This cohort study of 11,868 adolescents found evidence of shared vulnerability for adolescents who used cannabis at any point during the study period and who reported a greater number of psychosis spectrum symptoms and more distress from symptoms relative to those who never used cannabis. In line with a self-medication hypothesis, psychosis spectrum symptoms and reported distress due to the symptoms increased in the period leading up to the initiation of cannabis, while there was mixed evidence for increased psychosis symptoms post-initiation of cannabis (that is, contributing risk).
Using models of discontinuous growth curves, trajectories of psychosis spectrum symptoms were studied before and after initiating cannabis use. The investigation controlled for various variables: age, sex, internalizing and externalizing symptoms, socioeconomic status, parental mental health, and other substance use.
These findings underscore the importance of accounting for shared vulnerability and self-medication effects when modeling cannabis–psychosis risk associations, particularly in adolescents.
Reference: Osborne KJ, Barch DM, Jackson JJ, Karcher NR. Psychosis Spectrum Symptoms Before and After Adolescent Cannabis Use Initiation. JAMA Psychiatry. Published online November 6, 2024. doi:10.1001/jamapsychiatry.2024.3525
