Cannabis use in Adolescence and Risk of Psychosis: Are there Factors that Moderate this Relationship? A Systematic Review and Meta-Analysis

Abstract

Background Previous research has reported increased risk for psychosis among individuals who use cannabis during adolescence. We conducted a systematic review and meta-analysis to investigate the interaction between adolescent cannabis use and other factors in moderating risk for psychosis later in life. Method We searched four electronic databases in June 2020 for articles that assessed adolescent cannabis use, had psychosis as an outcome and analyzed for the association between adolescent cannabis use and psychosis. Analysis was done using random-effects meta-analysis and narrative synthesis. Results A total of 63 studies were included in the narrative review and 18 studies were included in the meta-analysis. Adolescent cannabis use was found to increase risk for psychosis (RR = 1.71 (95%CI, 1.47–2.00, p < 0.00001) and predict earlier onset of psychosis. The following factors moderate the relationship between cannabis use and the risk of psychosis: age of onset of cannabis use, frequent cannabis use, exposure to childhood trauma, concurrent use of other substances and genetic factors. Conclusion Adolescent cannabis use is associated with an increased risk for psychosis later in life. In addition, there are factors that moderate this relationship; therefore there is a need for research to assess the interaction between these factors, adolescent cannabis use and psychosis risk.

Associations of Cannabis Use across Adolescence and Early Adulthood With Health and Psychosocial Adjustment in Early Adulthood and Midadulthood in Men

“…These outcomes included 2 indicators of general adjustment (ie, income level and housing insecurity) and 3 indicators of psychopathology (ie, depressive symptoms, psychosis symptoms, and attention problems). The significant prediction of cannabis use to psychosis symptoms is in line with the findings of numerous prior studies (eg, Kiburi et al 44 ), and this effect was not attenuated by the significant association of childhood externalizing with psychosis symptoms in adulthood. The finding is of particular concern—given first, that higher levels of psychosis symptoms relate to poorer quality of life in adulthood; 70 second, that many cannabis products have become stronger in recent years; 71 and third, that rates of both cannabis use and cannabis use disorder in the U.S. have each increased in nearly all demographic groups in recent years 8 —leading to concerns that the effect of use on psychosis symptoms may become more severe and affect more individuals in the future.…”

“…A number of reviews indicate cannabis use, particularly frequent use, increases risk for later psychosis symptoms, 43 and a recent meta-analysis by Kiburi et al 44 of 18 studies supported that adolescent cannabis use increased risk for psychosis and predicted earlier onset of psychosis. Few studies, however, have extended from childhood to midlife, with controls for childhood predispositions and for use of alcohol.…”

Public Health Implications of Cannabis Legalization: An Exploration of Adolescent Use and Evidence-Based Interventions

“…Adolescent cannabis use was also positively correlated with an increased risk for psychosis; however, the correlation does not indicate any causation. This association between increased risk for psychotic events, psychosis, and relapsing psychosis for adolescent cannabis use has also been well documented in a number of studies [ 23 ]. The moderating variables for the development of psychosis are frequency and amount of cannabis use and the potency of the drug.…”

“…There is an abundance of evidence from multiple studies, including systematic reviews, which demonstrates how cannabis use affects adolescent development of psychiatric disorders [21][22][23][24][25][26]. As indicated by Radhakrishnan et al (2014), youth exposure to cannabinoids, which would include Spice and K2, underlies some of the transient psychiatric symptoms that mimic psychosis.…”

Persistent Childhood and Adolescent Anxiety and Risk for Psychosis: A Longitudinal Birth Cohort Study

“…We also controlled for cannabis use at 15 years, due to adolescent cannabis use being related to anxiety and being a risk factor for PD and PEs (40,41).…”