Does Legalizing Drugs Help or Hurt Mental Health? What 55 Studies Found

Scoping review following JBI guidelines and PRISMA-ScR checklist. Searched Medline, EMBASE, CINAHL, PsycInfo, and Web of Science for studies published January 2001 to December 2024. Included studies examining non-SUD mental health outcomes related to drug decriminalization, legalization, or commercialization. 55 studies met inclusion criteria.

Mental health impact is one of the most emotionally charged arguments in the legalization debate. This systematic mapping of the evidence provides a counterweight to both extremes—neither the claim that legalization causes a mental health crisis nor the claim that it's entirely benign is well-supported by the available evidence. The nuance matters for policy.

This provides important context for RTHC-00163's finding that the cannabis-psychosis association disappeared after adjusting for other substance use, and for RTHC-00162's review noting stable teen use despite legalization. At the population level, the mental health evidence is more reassuring than the individual-level studies might suggest. The distinction between population-level effects (which this review covers) and individual-level risk (which studies like RTHC-00163 examine) is crucial for interpreting the overall evidence base.

Scoping reviews map the literature without assessing study quality or conducting meta-analysis. The 55 included studies varied widely in methodology, populations, and how they measured mental health. Most evidence comes from cannabis legalization in North America—less data on other drugs or other regions. Population-level null effects can mask important subgroup effects. Only English-language studies included.