A recent study by Mass General Brigham researchers has found a significant increase in cannabis use and cannabis-related disorders among adolescents seeking psychiatric emergency care after the legalization of recreational cannabis in Massachusetts. The findings, published in the American Journal of Preventive Medicine, focus on data from Massachusetts General Hospital (MGH) following the start of legal retail sales to adults aged 21 and older in November 2018.
The study analyzed electronic health records from 7,350 psychiatric emergency service visits at MGH between January 1, 2017, and December 31, 2019. It included patients aged 12 to 70 and compared rates before and after retail sales began. Cannabis use was determined through urine tests, while cannabis-related disorders were identified using ICD-10 diagnosis codes.
Researchers observed that adolescents aged 12 to 17 experienced an almost fourfold increase in positive THC tests after commercialization—from 5% to over 17%. Similarly, diagnoses of cannabis-related disorders rose from 3.2% to 12.1% for this age group. No other age group showed a significant increase in cannabis-related disorders during the same period.
"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.
Foo noted that previous research has largely focused on the general population and has not shown significant changes in self-reported adolescent cannabis use following legalization. However, this new study highlights increased vulnerability among adolescents with psychiatric illnesses.
"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," Foo said.
The authors caution that their findings are based on single-site data from MGH and may not be generalizable statewide or nationally. They recommend further studies across different settings and states for broader understanding. Since the time period studied ended in December 2019, there are now over ten times more dispensaries operating in Massachusetts than during the original research window.
"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."
