Steroid use among U.S. teens has been on the rise since the early 1990s, but some groups of teens are using more than others. According to a new study of anabolic-androgenic steroid (AAS) abuse based on sexual preferences, gay male teens use steroids at a rate six times higher than their straight counterparts.

The study, published Monday in the journal Pediatrics, found that about 4 percent of heterosexual male teens reported using muscle-building steroids at some point in their lives. Less than 1 percent of straight male adolescents said they used steroids more than 40 times.

The rates of steroids use among gay male teens, however, were much higher. According to the report, 21 percent of gay adolescents said they had used steroids, and 4 percent of them admitted to using them more than 40 times.

"It's a bit sad that we saw such a large health disparity," study co-author Aaron Blashill, a psychologist and scientist with the Fenway Institute, the research arm of a Boston health center that treats gays and lesbians, told the Associated Press. "Given the dramatic disparity ... it would seem that this is a population in which greater attention is needed.”

Researchers surveyed more than 17,000 adolescent males -- 635 of them identified as gay or bisexual -- using data from the 2005 and 2007 Youth Risk Behavior Surveys. The national survey monitors several types of health-risk behaviors among youth and adults that contribute to the leading causes of death and disability, including drug use.

“This is the first known study to test and find substantial health disparities in the prevalence of AAS misuse as a function of sexual orientation,” researchers wrote. “Prevention and intervention efforts are needed for sexual minority adolescent boys.”

The caveat is that the surveys rely on self-reporting, so the results are based on the assumption that those who responded were telling the truth. Also, the survey does not account for teens who may still be in the closet.

The study authors don’t provide a clear explanation for the disparity in steroid use between gay and straight male teens, but health experts have a few theories. Some say gay teens are more likely to be bullied in school, and that their steroid use becomes a way to protect themselves.

Others suggest gay teens are more concerned with physical appearance than straight teens. Researchers speculate gay male adolescents take steroids as an extreme way to look more attractive.

"Generally speaking, the gay male subculture places a greater emphasis on physical appearance than straight men do," Marla Eisenberg, an associate professor with the department of pediatrics at the University of Minnesota, told HealthDay.

Heavy steroid use among teens has been linked to ligament and tendon tears, kidney and liver damage, heart disease, impotence and cancer, among other health problems.

“Unlike pro athletes, teenagers are much more susceptible to the physiological and psychological effects of steroids because of the natural hormonal imbalance associated with adolescence,” William Kashatus, a baseball historian and writer, stated in a 2013 article on steroid use among U.S. teens. “The effects include irritability, rage, depression and suicidal tendencies. What’s more, the psychiatric symptoms associated with steroid withdrawal persist for a year or more after the abuser stops using.”