Recreational Cannabis Laws Were Linked to a Small Increase in Suicide Deaths, But Results Varied by State | Research

The takeaway

Recreational marijuana laws were associated with an increase of 0.68 suicide deaths per 100,000 population overall, but the effect varied dramatically by state, with some early-adopting states actually seeing decreases.

Cannabis policy researchers, suicide prevention advocates, state legislators evaluating legalization impacts.

Suicide trends post-legalization varied dramatically: some states saw increases, others saw decreases

What the researchers found

RMLs were associated with a statistically significant increase of 0.68 suicide deaths per 100,000 population overall. The increase was primarily driven by states legalizing in 2018 (Maine, Vermont, Michigan) and 2019 (Illinois). In contrast, states that enacted RMLs in 2015 (Alaska, Oregon, Washington D.C.) experienced a decline in suicide deaths post-legalization.

Why it matters

The divergent results across states suggest that the relationship between cannabis legalization and suicide is not straightforward. State-specific factors, including how legalization is implemented, demographic characteristics, and mental health infrastructure, may be more important than legalization itself.

The numbers in context

Overall RML effect: +0.68 suicide deaths per 100,000 (p<0.05); 2018 and 2019 legalizing states drove the increase; 2015 legalizing states (Alaska, Oregon, DC) saw decreases; data from 2000-2022; staggered DiD framework.

How the study worked

Staggered difference-in-differences analysis of state-level age-adjusted suicide rates from CDC Multiple Cause of Death Files (2000-2022), using RML implementation dates from NORML to compare suicide trends in states before and after legalization.

What this study cannot tell us

Ecological study design (state-level data) cannot establish individual-level causation. Cannot control for all state-level confounders that changed alongside legalization. The COVID-19 pandemic overlapped with several states' legalization periods. Small number of states in each legalization cohort limits statistical power.

How to read the evidence

Moderate: Rigorous staggered difference-in-differences design using two decades of data, though ecological design and state-level heterogeneity complicate interpretation.

When this study was published

Published in 2025 with data from 2000-2022.

The bigger picture

This study adds nuance to the cannabis-suicide literature by showing that the direction and magnitude of the association depend heavily on which states are examined. This heterogeneity suggests that factors beyond cannabis access, such as implementation strategies and local context, shape outcomes.

Questions still open

What specific state-level factors explain the divergent suicide trends? Did the COVID-19 pandemic confound the results for later-legalizing states? Would individual-level data show different patterns than state-level ecological analysis?

Common questions

Why did some states see suicide increases and others decreases after legalization?

The study could not determine the specific reasons. Possible explanations include differences in implementation strategies, existing mental health infrastructure, demographic characteristics, concurrent policy changes, and timing relative to the COVID-19 pandemic.

Does cannabis legalization cause suicide?

This ecological study found a statistical association at the state level, but cannot prove causation. The dramatically different outcomes across states suggest that legalization itself is not the primary driver and that context-specific factors play a larger role.

Read the original research

Recreational Marijuana Laws and suicide deaths in the US.

Psychiatry research, 345, 116386

View on PubMed ↗Publisher’s paper ↗

Citation

Nayeem, Nawar; Messias, Erick; Lin, Ping-I. (2025). Recreational Marijuana Laws and suicide deaths in the US.. Psychiatry research, 345, 116386. https://doi.org/10.1016/j.psychres.2025.116386