Cannabis legalization had not led to an increase in substance use disorders or increased use of other illicit drugs and should not be considered a “gateway drug,” according to a study by researchers from the University of Colorado.
The study was published on January 5 in the Psychological Medicine journal.
“Recreational legalization was associated with increased cannabis use and decreased [alcohol use disorder] symptoms but was not associated with other maladaptations. … Moreover, vulnerabilities to cannabis use were not exacerbated by the legal cannabis environment.” — “Recreational cannabis legalization has had limited effects on a wide range of adult psychiatric and psychosocial outcomes,” Jan. 5, 2023, Psychological Medicine
The researchers also found no link between cannabis legalization and cognitive, psychological, social, relationship, or financial problems.
Lead author Stephanie Zellers, who began the research as a graduate student at CU Boulder’s Institute for Behavioral Genetics, told KDVR that the study’s “results are reassuring” from a public policy perspective.
“We really didn’t find any support for a lot of the harms people worry about with legalization,” she said.
Researchers from CU Boulder, the University of Colorado Anshutz Medical Campus, and the University of Minnesota used data from the Institute for Behavioral Genetics and the Minnesota Center for Twin Family Research to study 4,000 twins to conduct the research. The twins came from Colorado, which has legalized cannabis for adult use and Minnesota, where it remains illegal. The researchers found that identical twins living in states where cannabis is legal used it 20% more frequently; but when they compared results and looked at cannabis use disorder, use of alcohol and illicit drugs, and psychotic behavior, the research found no correlation to legalization.
Additionally, the study found that twins who lived in states where cannabis is legal showed fewer symptoms of alcohol use disorder.
A study published last year in the Journal of Adolescent Health came to a similar conclusion, finding that cannabis legalization did not lead to “dramatic increases in the use of alcohol, cigarettes, and non-prescribed opioids.”
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