Study: California Marijuana Legalization Linked to Decline in Heavy Alcohol Use Among Middle-Aged Adults

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For the study, researchers from Kaiser Permanente and the University of California examined over 8 million alcohol screening results collected from more than 3.5 million patients at Kaiser Permanente Northern California over a four year period. The study focused on two key events: the passage of adult-use marijuana legalization in November 2016 and the start of legal sales in January 2018. “Statistically significant, gradual declines in rates of both exceeding weekly alcohol limits and frequent heavy episodic drinking followed adult cannabis legalization passage”, states the study’s researchers.

The impact varied by age. Adults aged 35 to 64 experienced the most consistent reductions in heavy drinking. Young adults initially saw a short-term increase in heavy drinking, but this was followed by a gradual decline. Older adults 65 and over showed modest decreases, while those aged 50 to 64 experienced a short-lived uptick in exceeding weekly limits, which later declined. Exploratory analysis in those aged 18 to 20—who were still below the legal cannabis use age—revealed a non-significant rise in heavy drinking.

Researchers note that while the results are associative and do not prove causation, the study adds to growing evidence that marijuana legalization may influence alcohol consumption patterns.

The study’s findings come just weeks after the head of the company behind major liquor brands like Jack Daniel’s and Woodford Reserve said in an earnings call that the legalization of cannabis and the rise in marijuana use as a substitute for alcohol is putting noticeable pressure on the alcohol industry.

In Canada, Canadians are drinking less alcohol while spending more on marijuana, according to a report released earlier this year by Statistics Canada.