Changes in Rates of Suicide by Mass Shooters, 1980-2019.

Objective: The rate of worldwide mass shootings increased almost 400% over the last 40 years. About 30% are followed by the perpetrator's fatal or nonfatal suicide attempt.

Method: We examined the rate of fatal and nonfatal attempts among 528 mass shooters over the last 40 years and their relationship to detected mental illness to better understand this specific context of suicide. We collected information on U.S.-based, personal-cause mass murders that involved one or more firearms, from online sources.

Results: A greater proportion of mass shooters from 2000 to 2019 took or attempted to take their own lives (40.5%) compared with those from 1980 to 1999 (23.2%, p < 0.001). More than double the proportion of perpetrators who made a fatal or nonfatal suicide attempt had a history of non-psychotic psychiatric/neurologic symptoms (38.9%), compared with perpetrators who did not make a fatal or nonfatal suicide attempt (18.1%; p < 0.001). Among mass shooters who made fatal or nonfatal suicide attempts, 77 of 175 (44%) did not have any recorded psychiatric, neurologic, or substance use condition. Of the 98 mass shooters who made fatal or non-fatal suicide attempts and had a psychiatric, substance use, or neurologic condition, 41 had depressive disorders.

Conclusion: It is possible that a lack of information about the perpetrators' mental health or suicidal ideation led to an underestimation of their prevalence. These data suggest that suicide associated with mass shootings may represent a specific context for suicide, and approaches such as psychological autopsy can help to ascertain when psychiatric illness mediates the relationship between mass shootings and suicide.