Another federally funded study is suggesting that marijuana legalization may be linked to a “substitution effect,” with young adults in California “significantly” reducing their use of alcohol and cigarettes after the cannabis reform was enacted.
What’s more, the research appeared to contradict prohibitionist arguments about the potential impact of legalization, as the data also revealed no significant increase in marijuana use among young adults who were still not of age to access retail dispensaries—though there were interesting changes in certain modes of consuming cannabis following the policy change.
The study, published in the Journal of Psychoactive Drugs on November 24, involved surveys of people aged 18-20 living in Los Angeles before and after the state implemented adult-use legalization (AUL) of marijuana under a 2016 voter initiative. One cohort of 172 pre-legalization subjects were interviewed between 2014 and 2015, and the other 139 post-legalization subjects were surveyed between 2019 and 2020.
Researchers said that, “despite the possibilities of increased access to cannabis via diversion from the adult use market and increased normalization of cannabis use,” legalization “did not lead to increased frequency of cannabis use” among the subjects. They did notice a shift toward the use of edibles post-AUL, however.
“Some critics predicted that adult-use legalization would lead to increased other drug use” via the so-called “gateway theory.”
“Regarding other licit substance use, we observed significantly fewer days of alcohol and cigarette use among the [post-legalization] cohort compared to the [pre-legalization] cohort,” the study says. This suggests the “possibility of a protective effect offered by cannabis, including edibles, or potentially ongoing changes in norms and attitudes toward these substances within this socio-historical context.”
“Lower frequency of alcohol and tobacco use coupled with increase in edibles use post-AUL may suggest a substitution effect, which could result from increasing access to cannabis through a medical cannabis recommendation or diversion of cannabis from medical or adult use cannabis dispensaries,” the researchers state.
The study, which was funded by the National Institute on Drug Abuse, also found that changes in the use of illicit and nonprescribed drugs “did not significantly differ” between pre-legalization and post-legalization cohorts, which the researchers said is “notable since some critics predicted that AUL would lead to increased other drug use” via the so-called “gateway theory.”
“Future studies should monitor whether stable rates of cannabis use and declines in alcohol and cigarette use will be sustained as some participants reach legal age to access these substances for adult use, and how these trends continue or alter as participants enter later emerging adulthood,” the study concludes.
While one of the limitations of the study is the fact that people under 21 cannot legally purchase alcohol or tobacco, the findings regarding a possible substitution effect have been echoed in numerous studies covering different jurisdictions across the country, at least when it comes to other substances such as opioids.
Legalizing medical marijuana has been associated with a “lower frequency” of nonprescribed opioid use.
For example, legalizing medical marijuana is associated with a “lower frequency” of nonprescribed pharmaceutical opioid use, according to a November study published in the International Journal of Mental Health and Addiction.
In August, a federally funded study found that marijuana was significantly associated with reduced opioid cravings for people using them without a prescription, suggesting that expanding access to legal cannabis could provide more people with more options.
A separate study published in October found that legal access to CBD products led to significant reductions in opioid prescribing, with state-level drops of between 6.6 percent and 8.1 percent fewer prescriptions.
A report from July, meanwhile, linked medical marijuana use to lower pain levels and reduced dependence on opioids and other controlled substances.