Spillover Effects of Police Killings on the Mental Health of African-Americans in the United States

Background: Police kill over 300 African-Americans – at least a quarter of them unarmed – each year in the United States. These events may have spillover effects on the mental health of people not directly affected.

Methods: We estimated difference-in-differences regression models - adjusting for state-month, month-year, and interview day fixed effects, as well as age, gender, and educational attainment - to estimate the causal impact of police killings of unarmed African-Americans on self-reported mental health of other African-Americans in the United States general population. We combined novel data on police killings with individual-level data from the nationally representative 2013-2015 U.S. Behavioral Risk Factor Surveillance Surveys. We additionally assessed the timing of effects, the specificity of the effects to African-Americans, and the robustness of our findings.

Findings: Nearly half of the 103,710 African-American respondents were exposed to one or more police killings of unarmed African-Americans in their state of residence in the quarter prior to the survey. Each additional police killing of an unarmed African-American was associated with 0·14 additional poor mental health days (95% CI: 0·07-0·22; p<0·001) among African-American respondents. Population wide, the estimates imply nearly 55 million additional days of poor mental health among African Americans each year, The largest effects on mental health occurred in the 1-2 months after exposure, with no effects found for respondents interviewed before police killings (falsification test). The estimated mental health impacts were not observed among White respondents and resulted only from police killings of unarmed African-Americans (not unarmed Whites or armed African-Americans).

Interpretation: Police killings of unarmed African-Americans have adverse effects on mental health among African-American adults in the general population. Evidence-based programs should be implemented to decrease the frequency of police killings and to mitigate adverse mental health spillovers within communities when such killings do occur.