The Fund supports networks of state health policy decision makers to help identify, inspire, and inform policy leaders.
The Milbank Memorial Fund supports two state leadership programs for legislative and executive branch state government officials committed to improving population health.
The Fund identifies and shares policy ideas and analysis to advance state health leadership, strong primary care, and sustainable health care costs.
Keep up with news and updates from the Milbank Memorial Fund. And read the latest posts from our staff and guest authors.
The Fund publishes The Milbank Quarterly, as well as reports, issues briefs, and case studies on topics important to health policy leaders.
The Milbank Memorial Fund is is a foundation that works to improve population health and health equity.
July 29, 2026
Quarterly Article
Sarah B. Windle
Peter M. Socha
Jasleen Arneja
Sam Harper
Genevieve Gore
Geneviéve Gariépy
Eva Graham
Arijit Nandi
June 2026
Mental Health and Substance Use Challenges
Back to The Milbank Quarterly
Policy Points:
Context: Substantial changes in cannabis policies are occurring globally; however, the impacts of these reforms on cannabis use, as well as downstream effects on other substance use, remain unclear.
Methods: We conducted a systematic review to identify studies examining the impact of a cannabis policy change on substance use. We searched Embase, Medline, PsycINFO, the Web of Science Core Collection, and the Criminal Justice Database, as well as gray literature sources including the Social Science Research Network. The included studies employed a quasi-experimental approach and were assessed for risk of bias using a modified version of ROBINS-I to facilitate the assessment of these designs. The findings were synthesized using a descriptive, analytical approach.
Findings: The included reports (N = 176) were published between 1993 and 2024, with approximately two-thirds published after 2019. Most were peer-reviewed publications (n = 148) applying a difference-in-differences (n = 129) or interrupted time series (n = 42) approach to data from the United States (n = 141). Medical and recreational cannabis legalization may increase cannabis initiation across age groups, with increased prevalence of cannabis use among young adults and adults and inconsistent evidence among youth. The impacts on alcohol use were differential by policy and age group, with potential decreases following medical legalization and potential increases following recreational legalization among young adults. Evidence from a limited number of studies suggested potential decreases in tobacco use among all age groups. Most studies found no change or a decrease in opioid-related outcomes, although evidence was less consistent for opioid-related mortality. We found few studies examining cannabis decriminalization, with no clear evidence of changes in cannabis or other substance use.
Conclusions: Overall, these findings suggest that medical and recreational legalization increase cannabis use, with weaker effects among youth. In addition, potential substitution effects were identified for other substances (e.g., alcohol, tobacco, opioids), excepting complementary alcohol use among young adults following recreational cannabis legalization.
