The Effect of Legalizing Online Sports Gambling on Population Mental Health

Importance: The rapid rise of online sports gambling in the U.S. has been associated with financial harms, raising concern that it may adversely affect population mental health. Objective: To estimate the causal effect of state legalization of online sports gambling on population mental health, including a range of self-reported and registry-based outcomes. Design, Setting, and Participants: Repeated cross-sectional study using nationally representative Behavioral Risk Factor Surveillance System (BRFSS) data from 2014-2025 and registry-based mortality records from 2012-2024. We leveraged state-level variation in the legalization of online sports gambling and applied a stacked difference-in-differences with event study design. The analytic sample included 4,660,948 BRFSS respondents and mortality records for virtually all state-years. We estimated effects on all adults and several higher-risk subgroups, including men, young men, and men with lower educational attainment. Exposure: State legalization of online sports gambling. Main Outcomes and Measures: Self-reported outcomes included poor mental health days, depressive disorder diagnoses, ever binge drinking, number of binge drinking episodes, and marijuana use. Registry-based outcomes included suicide mortality and alcohol-induced mortality per 100,000. Results: Among 4,660,948 BRFSS respondents, 48.7% were men, 40.2% had no more than a high school education, and the mean age was 47.6 years. Legalization of online sports gambling had no discernible effect on poor mental health days of all U.S. adults (-0.01 days; 95% CI, -0.16 to 0.14; P=0.88), depressive disorder diagnoses (0.1 percentage points; 95% CI, -0.7 to 0.9; P=0.84), binge drinking, binge drinking episodes, or marijuana use. Meanwhile, mean suicide mortality was 14.1 per 100,000 and mean alcohol-induced mortality was 12.2 per 100,000. Legalization did not affect adult suicides (0.13 deaths per 100,000; 95% CI, -0.71 to 0.97; P=0.76) or alcohol-induced mortality (1.08 deaths per 100,000; 95% CI, -0.58 to 2.73; P=0.21). Results were null among men and higher-risk subgroups of men. Conclusions and Relevance: The legalization of online sports gambling has not produce detectable population-level changes in a range of mental health outcomes, including reported symptoms, diagnoses, substance use, and registry-based mortality due to suicide or alcohol, in up to 3 years of follow-up. These findings suggest that although online sports gambling may cause financial harm and severe distress for some individuals, legalization has not produced measurable average changes in population mental health over the observed follow-up period.