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October 17, 2023
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Connections between depression and cannabis strengthened with recreational legalization

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Key takeaways:

  • The accessibility of cannabis and the perception of its health benefits may have caused the association to strengthen.
  • The findings did not suggest causation or directionality of the effect.
Perspective from Ashley Poole, PsyD, LPC

The association between the prevalence of cannabis use and depression among young adults strengthened following the legalization of recreational cannabis, according to researchers.

A combination of cannabis use and depression appears to worsen both substance use disorder outcomes and mood, especially for young adults, Jeremy Mennis, PhD, a professor concentrating on environmental studies and geographic information systems at Temple University, and colleagues wrote in the American Journal of Preventive Medicine. But current research is not clear “as to whether heavy cannabis use causes depression, whether depression leads to cannabis use, or both mechanisms occur.”

medical_marijuana
The association between prevalence rates of cannabis use and depression among young adults strengthened following the legalization of recreational cannabis, according to researchers. Image: Adobe Stock

“The use of cannabis for medical purposes is increasing in the U.S., and evidence suggests that young adults are disproportionately more likely to use cannabis without medical supervision to cope with health problems (ie, self-medicate) than older adults, particularly for psychological problems,” they wrote. “Though evidence on the impact of recreational legalization is mixed ... a number of recent U.S. national and state-level studies have found that the prevalence of young adult cannabis use, as well as frequency of use, have disproportionately increased in states with recreational legalization following enactment.”

The researchers used the National Survey on Drug Use and Health to extract data on past-month cannabis use and depression. They also used moderated regression models to compare prevalence rates of depression and cannabis use in states that legalized recreational cannabis to those that did not.

Mennis and colleagues found that, following the legalization of recreational cannabis, the association between prevalence rates of cannabis use and depression among young adults strengthened — compared with before legalization (beta = 0.229; 95% CI, 0.049-0.409), the positive statistical effect of depression on cannabis use more than doubled in magnitude after legalization (beta = 0.564; 95% CI, 0.291-0.838). This represented a significant change (beta = 0.335; 95% CI, 0.093-0.577).

“These findings do not necessarily imply causation or directionality of the effect, and the use of state-level prevalence measures prohibits conclusions regarding individual cannabis use behaviors or the prevalence of cannabis use among young adults with depression,” they wrote. “Nonetheless, these results suggest that recreational legalization impacted the relationship between trajectories of prevalence rates of depression and cannabis use at the state level.”

Potential causes of the association strengthening, the researchers wrote, were increases in the accessibility of cannabis and the perception of the drugs’ health benefits, which may encourage young adults with depression to use cannabis as a coping mechanism.

“Future research should investigate the mediating role of perception of risk, perception of the health benefits of cannabis, and other cannabis-related attitudes and beliefs which may occur along the theorized pathway by which recreational legalization moderates the association of young adult depression with cannabis use,” Mennis and colleagues concluded.