Effect of cannabis liberalization on suicide and mental illness following recreational access: a state-level longitudinal analysis in the USA

Abstract

Background. We extend the model introduced by Anderson et al. [M.D. Anderson, D.I. Rees, J.J. Sabia, American Journal of Public Health 104, 2369-2376] to evaluate the public mental health implications of new developments in marijuana policy, such as recreational marijuana access and additional years of data on suicide mortality. Methods. We obtained state-level suicide data from the National Vital Statistics System's Mortality Detail Files for 1999-2018. We used panel regression analysis to examine the association between suicides per 100 000 population and both medical and recreational marijuana access. Three specifications of the equation were employed as a robustness test. Results. After adjusting for economic conditions, alcohol taxes and consumption, time effects, state fixed effects, and state-specific linear time trends, the legalization of recreational marijuana was associated with a 2.9% (95% confidence interval [CI] = -5.6, -.03) reduction in the suicide rate for the most rigorous specification, but didn't pass the robustness check at the P < .05 level for the other two specifications. However, recreational marijuana legalization was associated with a 5.4% reduction (95% CI = -9.4%, -1.4%) in suicide rates for males in the 40 to 49 age group, passing the robustness check for all specifications. Conclusion. Suicide rates among men in the 40 to 49 age group fell after recreational marijuana legalization compared with those in states that did not legalize, which is consistent with the results found by Anderson et al. for medical marijuana when that same population was younger. There was no consistent relationship between medical marijuana legalization and suicide rates for any population. Additionally, mental health indicators at the state level were unaffected by either recreational or medical marijuana legalization. We confirm the findings of Anderson et al. (2014), observing no consistent relationship between marijuana legalization and observable mental health outcomes. However, suicide rates increase at lower rates on average relative to other states following recreational marijuana legalization.

The highs and the lows: Recreational marijuana laws and mental health treatment

“…As it pertains to marijuana laws, many studies have and continue to employ quasi-experimental approaches to leverage the variation in legislation across states. Some studies find that MMLs are associated with decreased suicides (Anderson et al, 2014;Bartos et al, 2019;Grucza et al, 2015;Rich et al, 2022). Some studies find a weak relationship between state marijuana laws and mental health or suicide after accounting for confounding factors (Anderson et al, 2014;Leung, 2019).…”

“…Some randomized control studies find evidence that cannabinoids improve sleep, reduce symptoms of stress, and can have antidepressant quali‐ties (National Academies of Sciences et al., 2017). Other studies find that medical marijuana laws (MMLs) are associated with a decrease in suicides (Anderson et al., 2014; Bartos et al., 2019; Grucza et al., 2015; Rich et al., 2022). Conversely, some studies find a weak relationship between state marijuana laws and mental health or suicide after accounting for confounding factors (Anderson et al., 2014; Anderson & Rees, 2021; Leung, 2019).…”