(Medical Xpress)—Lesbian, gay, bisexual and transgender youth and those questioning their sexuality are at significantly greater risk of truancy and of considering and attempting suicide than their heterosexual classmates – even when bullying isn't involved, according to a new study of more than 11,000 middle and high school students.

Although bullying does account for a portion of the risk disparities, significant differences remain after taking bullying into account, said the authors, Joseph P. Robinson and Dorothy Espelage, educational psychologists at the University of Illinois.

Prior studies have indicated that LGBTQ are at greater risk for considering and attempting suicide and for unexcused absences. In the current study, which  assessed seventh through 12th graders across 30 schools, the researchers sought to determine if bullying explained LGBTQ youth's higher risks for these behaviors.

"Bullying does explain a substantial portion of the disparities between LGBTQ and straight students, suggesting that we need to have anti-bullying policies in schools, and that those policies should cover , and gender expression," Robinson said. "However, bullying is not the entire story."

Using a propensity-score-matching technique, the researchers matched heterosexual and LGBTQ students with similar and victimization profiles to examine how straight youths' risk levels were compared to LGBTQ youth when straight youth were bullied at the same rates as LGBTQ youth, and vice versa.

The researchers found that, in the matched samples, LGBTQ youth were still more than three times as likely as their to consider suicide. This pattern was found in both matched samples – that is, regardless of whether the researchers matched LGBTQ youth to similar heterosexual youth or vice versa. The researchers noted that the striking similarity in findings across both matched samples suggests that LGBTQ youth are at higher risk regardless of whether we look at differences among youth who are victimized more often or less often.

Robinson and Espelage then conducted supplemental analyses on a broader range of victimization variables, such as childhood sexual abuse, dating violence and parental physical abuse to determine if these variables explained the disparities in risk levels that remained after bullying was taken out of the equation. Even with these factors taken into account, LGBTQ students remained at significantly higher risk than their heterosexual peers.

Bisexual and questioning youth in particular appeared to be at significantly higher risk, but the researchers could only speculate why. Perhaps these groups are exposed to greater intolerance and stress than youth who identify as lesbian or gay. Or perhaps they are the targets of "biphobia" –  experiencing social rejection and discrimination from both heterosexual and lesbian/gay students, the researchers theorized.

Another possible factor that might explain the persistent differences between straight and LGBTQ youth could be stigmatizing messages about sexual minorities in children's immediate environments as well as broader society that exacerbate LGBTQ youths' feelings of depression, rejection and isolation, Robinson and Espelage suggested.

In May, the Illinois Senate narrowly voted down a bill approved by the Illinois House of Representatives that would have required school districts to implement aggressive and detailed anti-bullying policies. Conservative groups opposed the legislation out of concerns that the mandated programs would promote homosexuality and violate students' and parents' religious beliefs.

"Suicide isn't a trivial thing," Robinson said. "Our findings suggest that, even beyond bullying-prevention policies, schools should have additional policies that support safe learning environments for all students and help address the remaining risk that bullying alone does not account for."

The study appeared in the November issue of the journal Educational Researcher.