Association Between Marijuana Laws and Suicide Among 12- to 25-Year-Olds in the United States From 2000 to 2019

OBJECTIVE

Cannabis use is associated with suicide-related outcomes in both adolescents and adults, and may be increasing amid shifting cannabis policies. However, little is known about the impact of medical marijuana legalization (MML) and recreational marijuana legalization (RML) policies on youth suicide. Using 20 years of national data, we examined associations between MML, RML, and suicide-related mortality among US individuals aged 12 to 25 years, and assessed whether they varied based on age and sex.

METHOD

Suicide deaths (N = 113,512) from the 2000-2019 National Vital Statistics System Multiple Cause of Death files for age groups 12 to 13, 14 to 16, 17 to 19, 20 to 22, and 23 to 25 years were examined in relation to time-varying cannabis law status using a staggered adoption difference-in-difference (DiD) approach with a negative binomial regression to determine associations between MML, RML, and suicide rates, controlling for individual- and state-level covariates and accounting for the varying effective dates of MML and RML by state.

RESULTS

The overall unadjusted annual suicide rate was 10.93/100,000, varying from 9.76 (states without marijuana laws (ML)) to 12.78 (MML states) to 16.68 (RML states). In multivariable analysis, both MML (incidence rate ratio [IRR] = 1.10, 95% CI: 1.05-1.15) and RML (IRR = 1.16, 95% CI: 1.06-1.27) were associated with higher suicide rates among female youth compared to those in states without ML. Youth aged 14 to 16 years had higher rates of suicide in states with RML compared to states with MML (IRR = 1.14, 95% CI: 1.00-1.30) and states without ML (IRR = 1.09, 95% CI: 1.00-1.20). Findings were consistent across sensitivity analyses.

CONCLUSION

MML and RML were associated with increased suicide-related mortality in female youth and 14- to- 16-year-old individuals of both sexes. Mechanisms through which cannabis policies are related to increased youth suicide warrant further study and should inform legislative reform.

Legalization of Medical Cannabis and Site of Death: Evidence From National Vital Statistics Mortality Data

We examined whether Medical Marijuana Legislation (MML) was associated with site of death. Using state-level data (1992-2018) from the National Vital Statistics System (NVSS), we employed difference-in-differences method to compare changes in death rate among older adults at four sites-nursing home (NH), hospital, home, hospice/other-over time in states with and without MML. Heterogeneity analyses were conducted by timing of MML adoption, and by decedent characteristics. Results show a negative association between MML implementation and NH deaths. Among early adopters (states with weakly regulated programs) and decedents with musculoskeletal disorders, there was a positive association between MML implementation and hospital deaths, whereas among late adopters (states with "medicalized" programs), there was a positive association between MML implementation and hospice deaths. Decline in NH deaths may reflect increased likelihood of transfers due to threat of Federal enforcement, penalties for poor outcomes, and liability concerns. Future studies should examine these associations further.