Increased Use of Cannabis Seen Among Adolescents with Psychiatric Illnesses After Cannabis Sales Became Legal

A Mass General Brigham study found nearly a fourfold increase in cannabis use among adolescents in Massachusetts presenting for psychiatric emergency services after commercialization.

In November 2018, retailers in Massachusetts began selling recreational cannabis to adults 21 years and older. A study by investigators from Mass General Brigham found that, after commercialization, rates of cannabis use and cannabis-related disorders (i.e., cannabis use disorder, cannabis-induced psychiatric symptoms) disproportionately increased among adolescents, aged 12 to 17 years, presenting for a psychiatric emergency. The investigators found there was an almost fourfold increase in cannabis use for this age group, rising from 5% to more than 17%, and a similar increase in cannabis-related disorders, among people presenting at Massachusetts General Hospital (MGH) for psychiatric emergency services. Results of the study are published in the American Journal of Preventive Medicine.

“Young people with mental health challenges are more vulnerable to the negative effects of cannabis use, which can catalyze or worsen psychiatric symptoms. Our study found that more adolescents who were seeking help for a psychiatric emergency were using cannabis after commercialization became legal in Massachusetts. This suggests that those below the legal buying age could still access cannabis, perhaps through adults, poorly regulated online dispensaries, social media platforms, or other routes,” said corresponding author Cheryl Yunn Shee Foo, PhD, a clinical psychologist in the Mass General Brigham Department of Psychiatry.

While most research on the impacts of changing cannabis policies has focused on the general population, there is limited evidence regarding how cannabis commercialization affect psychiatric populations who are especially vulnerable to the negative effects of substance use. Foo set out to examine how the legalization and commercialization of retail cannabis in Massachusetts affected cannabis use and cannabis-related disorders among people seeking emergency psychiatric care.

To investigate this relationship, the study analyzed electronic health records from 7,350 psychiatric emergency service visits at MGH. The study included patients aged 12 to 70 and compared data before and after the retail sales of recreational cannabis began in Massachusetts, spanning January 1, 2017 to December 31, 2019. Cannabis use was determined through urine testing, while cannabis-related disorders were identified using ICD-10 diagnosis codes.

Researchers observed that adolescents presenting for a psychiatric emergency experienced the largest increase in tetrahydrocannabinol (THC) positive tests after commercialization compared to other age groups, jumping from 5% to 17.3%. Cannabis-related disorders also rose from 3.2% to 12.1% in this age group, whereas no other age group increased significantly in cannabis-related disorders. Prior studies on the impacts of recreational cannabis legalization in the general population, on the other hand, have consistently indicated no significant changes in self-reported adolescent cannabis use.

“Our study’s findings suggest that the greater accessibility, social acceptability, and advertising that comes with cannabis commercialization may negatively affect adolescents with psychiatric illnesses more than the general adolescent population or adults with psychiatric illnesses,” said Foo.

This study was conducted using records from MGH and generalizability is limited given the single-site data. Replication across other psychiatric populations and states is recommended. Additionally, there are over ten times more cannabis dispensaries in Massachusetts since the study period, suggesting even greater present-day effects.

“We’re seeing missed opportunities for education and prevention,” Foo said. “Further research is needed to examine the impact of cannabis policies on youth with psychiatric illnesses to inform targeted prevention efforts.”

Authorship: In addition to Foo, Mass General Brigham authors of the study Kevin Potter, A. Eden Evins, Abigail L. Donovan, and Corinne Cather. Additional authors include Abigail C. Wright, Kim T. Mueser, and Sharon Levy.

Disclosures: Donovan reported owning stock from Artisan, a privately held engineering company. Donovan’s spouse is on the Board of Artisan and owns stock in Mirah, a privately held healthcare company providing access to measurement-based care. Evins and Cather have served as consultants to Charles River Analytics (National Institute on Drug Abuse Small Business Innovation Research grant), outside the submitted work. Levy served as an expert witness for the city of Haverhill regarding cannabis legislation in 2024, outside the submitted work. No other financial disclosures were reported.

Funding: This research was supported by the Massachusetts Department of Mental Health to the Massachusetts General Hospital Center of Excellence for Psychosocial and Systemic Research.

Paper cited: Foo, CYS et al. “Effects of Legalizing Recreational Cannabis Sales on Cannabis Use and Cannabis-Related Disorder Among Presentations to a Psychiatric Emergency Service” American Journal of Preventive Medicine DOI: 10.1016/j.amepre.2025.108142