A nationwide rise in cannabis use is not the result of medical or recreational legalization in a growing number of states, according to a new study published in the journal Addiction.
"Medical and recreational marijuana policies did not have any significant association with increased marijuana use," reads the study. "Marijuana policy liberalization over the past 20 years has certainly been associated with increased marijuana use; however, policy changes appear to have occurred in response to changing attitudes within states and to have effects on attitudes and behaviors more generally in the U.S."
Researchers at the Public Health Institute’s Alcohol Research Group looked at data from National Alcohol Surveys and stacked its results on cannabis use against changes in state laws.
What the researchers discovered was that the increase in cannabis use was “primarily explained by period effects” – i.e. societal factors that impact populations across age and generational groups – and not by policy changes.
While the authors say a decrease in disapproval of cannabis could be one contributing factor, they insist the rise was not caused by legalization.
"The steep rise in marijuana use in the United States since 2005 occurred across the population and is attributable to general period effects not specifically linked to the liberalization of marijuana policies in some states," reads the paper's abstract.
The researchers add that respondents in earlier surveys taken prior to legalization might have been less likely to confess to cannabis use due to criminalization. What this suggests is that ending prohibition does not, in fact, lead to increased use; it simply makes people more likely to admit they consume cannabis in a survey.