People who have engaged in sexual activity with partners of the same sex are more likely to have experienced violence and, in turn, to suffer from post-traumatic stress disorder (PTSD), according to a new study published online April 15 in the American Journal of Public Health.

Traumatic events—such as combat violence, mistreatment or abuse as a child, and the unexpected death of a loved one—can lead to PTSD. What’s more, people with PTSD are at increased risk for depression, drug and alcohol abuse, and problems in relationships and employment. Previous studies have found that the lifetime risk for PTSD in adulthood in the general population is about 4 percent for men and 10 percent for women. In gays, lesbians, bisexuals and heterosexuals who have same-sex attractions or a history of sexual activity with the same sex—all classified as sexual minorities—the risk for PTSD climbs to 9 percent for men and 20 percent for women.

The new study, detailed in a release by researchers at Harvard School of Public Health in Boston, confirms these rates—it also documents the high prevalence of interpersonal violence experienced by sexual minorities, especially as children. Contributing factors can include not only violence, such as bullying in childhood and young adulthood, but also social isolation due to the stigma of same-sex attraction, sexual activity and relationships.

“Our study documents that profound sexual orientation disparities exist in exposure to violence and other traumatic events beginning in childhood,” said senior author Karestan Koenen, PhD. “Something about our society puts individuals with minority sexual orientations at high risk for victimization. This is a major public health problem that needs to be addressed.”