Recreational Cannabis Legalization Was Linked to Fewer Mental Health Treatment Admissions

A 2023 study found that states adopting recreational cannabis laws subsequently recorded fewer mental health treatment admissions. The result does not show that legalization improved mental health, however. It may reflect changes in treatment access, care-seeking behavior, or the use of cannabis as a substitute for formal treatment.

Published in Health Economics, Alberto Ortega’s study examined state-level data from 2007 through 2019. Ten states adopted recreational marijuana laws during that period. Ortega analyzed admissions data from the Substance Abuse and Mental Health Services Administration’s Uniform Reporting System, which includes information from state mental health agencies and covers both inpatient and outpatient services.

Using an event-study and difference-in-differences approach, Ortega compared treatment trends before and after states adopted recreational marijuana laws with trends in states that had not yet adopted them. The analysis found no meaningful differences in pre-law trends, followed by a statistically significant decline in admissions after legalization.

In the study’s main estimate, mental health treatment admissions fell by roughly 37% in the early years after adoption—about 92 fewer admissions per 10,000 residents. The decline became larger over time and remained negative through the fourth year after a law was adopted.

The reductions were concentrated among people under 65 and among Black and white patients. Admissions declined for both men and women, with estimated decreases of about 42% for men and 37% for women. Medicaid-funded admissions also fell significantly, while the smaller decrease among non-Medicaid admissions was not statistically significant. Hispanic admissions and admissions among people 65 and older did not show the same statistically significant pattern.

Because the study measured treatment admissions rather than mental health directly, the findings should not be interpreted as evidence that cannabis legalization made people healthier. Ortega’s additional analysis of self-reported mental health found no clear effect, and the study could not determine whether fewer admissions reflected improved symptoms, reduced access to care, lower willingness to seek treatment, or greater reliance on cannabis outside the formal health system.

Self-medication is one possible explanation. Some people may have used cannabis to manage symptoms instead of entering treatment after recreational use became legal. Another possibility is that changes in policy or public attitudes altered how facilities or patients approached treatment. The study found no overall change in facility revenue, but its data could not directly test these mechanisms.

The uncertainty is important because cannabis itself has mixed and potentially harmful mental-health effects. The Centers for Disease Control and Prevention notes that cannabis use is associated with anxiety, depression, psychosis, and schizophrenia, although the relationships are complex and not fully understood.

Ortega’s results are therefore best read as evidence of a change in mental health treatment utilization after recreational cannabis laws were adopted—not as proof that legalization improved mental health or that cannabis is an effective replacement for professional care. More research is needed to determine whether the decline represents reduced need, treatment avoidance, changes in the delivery of services, or another consequence of legalization.