Cannabis has recently been legalized for nonmedical purposes in many US states and countries such as Canada and Uruguay. Although many report cannabis use with minimal to no adverse effects, prolonged use of cannabis in adolescents can lead to greater risk of impaired cognitive functioning which can result in developmental, educations, and employment effects. Although many states and countries have put age restrictions on the purchase of cannabis, adolescents below this age cutoff have historically had the highest rates of substance use. This has led many to wonder if the recent legalization of nonmedical cannabis use has increased rates of cannabis use in the young adult age group. This study examines cannabis consumption before and after legalization of nonmedical cannabis in adolescents and young adults.
This study is a systematic review that included 32 articles that were published between 2016 and 2021. The studies were identified using MEDLINE, PubMED, PsycINFO, Scopus, and Web of Science. Inclusion criteria included original, peer reviewed studies that focused on individuals age 10-24 and examined change in cannabis consumption before and after the legalization of nonmedical use. The studies were grouped by cannabis consumption measures and into two age groups: adolescents (12-17 years old) and young adults (18-25 years old). Data was analyzed using a narrative synthesis technique which took into account the quality of the study.
Results of the data analysis showed that more than half of the studies reported nonsignificant changes in cannabis use before and after legalization. When examining only higher quality studies, 40% of outcomes indicated a statistically significant increase in cannabis consumption after legalization, while in 5% of outcomes legalization was associated with a decrease in use, and 55% of outcomes were associated with no change in use. In adolescents, no change in cannabis consumption was reported in 58% of outcomes, 25% reported an increase, and 16% reported a decrease. In young adults, 42% of outcomes were correlated to a statistically significant increase in consumption and no studies indicated a decrease in use. Subgroup analysis indicated that women and adolescents that displayed alcohol binge-drinking behaviors were more likely to increase cannabis consumption following legalization .
Takeaway: The legalization status of cannabis may provide some predictive value when assessing rates of cannabis consumption in adolescents and young adults.