Sexual minorities, especially women, who misuse substances more likely to have psychiatric disorders

More than half of lesbian, gay and bisexual individuals who misuse alcohol or tobacco also have a co-occurring psychiatric disorder, compared to one-third of heterosexuals, a new University of Michigan study finds.

"The degree of disparities in alcohol, tobacco and other psychiatric disorders by sexual identity was very surprising," said Rebecca Evans-Polce, assistant research scientist at the U-M School of Nursing and first author of the study. "The differences for women are more striking."

For example, 63% of bisexual women who misused tobacco also had a psychiatric issue—anxiety or mood disorder or PTSD—compared to 46% of heterosexual women with a tobacco use disorder. Among those who met criteria for a past-year tobacco use disorder, bisexual women were also more likely to have PTSD (31%) compared with heterosexual women (13%), she said.

Discrimination, stress and childhood trauma were associated with greater odds of psychiatric disorders among lesbian, gay or bisexual individuals, with greater social support inversely associated with tobacco use disorder and coexisting psychiatric disorders.

Studies have shown that lesbian, gay and bisexual individuals have greater risk for both substance use disorders and psychiatric disorders, and the prevalence varies by gender. The U-M study is one of the few that looks at whether they are at greater risk for substance use disorders and co-occurring psychiatric disorders, Evans-Polce said.

Bisexual women, compared to heterosexual women, had a particularly high prevalence of anxiety disorders, (32.5% vs. 16% heterosexual), mood disorders (35% vs. 15% heterosexual) and post-traumatic stress disorder (21% vs. 6% heterosexual).

One of the largest differences was that bisexual individuals (18%) overall were four times more likely to have PTSD than heterosexuals (4%). Bisexual men had a particularly high prevalence of past-year alcohol use disorder (31% vs. 17% heterosexual) and tobacco use disorder (41% vs. 23% heterosexual).

More research is needed to understand why studies repeatedly find such high risk for bisexual women. One reason could be that women experience more stress and trauma.

"In addition, combined social inequities and stress resulting from both sexism and heterosexism may contribute," Evans-Polce said. "Other factors identified in research by our (Center for the Study of Drugs, Alcohol, Smoking and Health) have shown that bisexual women also report much earlier onset of alcohol use and are more likely to experience adverse childhood experiences."

The findings underscore the importance of mental health screening for sexual minorities with alcohol or tobacco use disorders, she said. Evans-Polce and colleagues analyzed 35,796 responses from the National Epidemiologic Study on Alcohol and Related Conditions-III.