As many countries consider changing cannabis policies, a new study by Carnegie Mellon University researcher Jonathan P. Caulkins looked at cannabis use in the United States from 1979 to 2022. The study found that more people now report using cannabis daily or almost daily than those who drink alcohol that often. It also concludes that long-term changes in cannabis use match policy changes over the same time period. The study is published in Addiction.
“The data come from survey self-reports, but the enormous changes in rates of self-reported cannabis use, particularly of daily or near-daily use, suggest that changes in actual use have been considerable,” says Jonathan P. Caulkins, professor of operations research and public policy at Carnegie Mellon’s Heinz College, who conducted the study. “It is striking that high-frequency cannabis use is now more commonly reported than is high-frequency drinking.”
Unlike previous research that compared cannabis and alcohol outcomes before and after state-level policy changes, this study looked at long-term trends for the entire United States. Caulkins focused on days of use, not just how common it was, and compared the results to alcohol, but did not try to find causes.
The study used data from the U.S. National Survey on Drug Use and Health (and its predecessor, the National Household Survey on Drug Abuse), looking at more than 1.6 million respondents across 27 surveys from 1979 to 2022. Caulkins compared rates of use in four key years that reflected major policy changes: 1979, 1992, 2008, and 2022. The study found:
- Reported cannabis use was lowest in 1992, with some increases through 2008 and significant growth since then, especially for measures of more intensive use.
- Between 2008 and 2022, the per capita rate of reporting past-year use increased 120%, and days of use reported per capita increased 218% (from 2.3 billion to 8.1 billion days per year).
- From 1992 to 2022, the per capita rate of reporting daily or near-daily use rose 15-fold. In 1992, there were 10 times as many daily or near-daily alcohol users as cannabis users (8.9 million versus 0.9 million), but in 2022, for the first time, there were more daily and near-daily users of cannabis than of alcohol (17.7 million versus 14.7 million).
- While more people drink than use cannabis, high-frequency drinking is less common. In 2022, the median drinker reported drinking on 4-5 days in the previous month versus using cannabis on 15-16 days. In 2022, prior-month cannabis consumers were almost four times as likely to report daily or near-daily use (42% versus 11%) and 7.4 times more likely to report daily use (28% versus 3.8%).
“These trends mirror changes in policy, with declines during periods of greater restriction and growth during periods of policy liberalization,” explains Caulkins. He notes that this does not mean that policy drove changes in use; both could have been manifestations of changes in underlying culture and attitudes. “But whichever way causal arrows point, cannabis use now appears to be on a fundamentally different scale than it was before legalization.”
Caulkins acknowledges that the study has limitations, such as relying on self-reported data from general population surveys, lacking validation from biological samples, and excluding certain subpopulations that may use at different rates than the rest of the population.
