By Andrew M. Seaman

NEW YORK (Reuters Health) - People who are gay, lesbian or bisexual tend to die earlier in communities where citizens are less accepting of same-sex relationships, according to a new study.

"The size of the relationship between anti-gay prejudice and mortality was large," Mark Hatzenbuehler told Reuters Health.

"This research indicates that reducing prejudice may improve the life expectancy of sexual minorities in the United States," he added in an email.

Hatzenbuehler is the study's lead author from the Mailman School of Public Health of Columbia University in New York.

He and his colleagues write in the journal Social Science and Medicine that although it has been thought that the amount of prejudice or stigma in a community is tied to the health of its residents, it has been hard to measure stigma.

To give that a try, the researchers used data from the General Social Survey, which was conducted annually beginning in 1972 and then every other year after 1994.

The survey asked a group of U.S. adults about their social attitudes, including anti-gay prejudice, through questions such as, "Do you think that sexual relations between two adults of the same sex is always wrong, almost always wrong, wrong only sometimes, or not wrong at all?"

Participants were also asked whether their sexual partners were exclusively male, female or both.

Hatzenbuehler's team linked responses from participants surveyed in 1988 through 2002 to national death records to see how many had died by 2008 and whether there were differences tied to the amount of anti-gay stigma in their communities.

Overall, there were data from 21,045 people. Of those, about 4 percent said they had been involved in same-sex relationships.

By the end of the study, about 92 percent of people from low-stigma areas who said they were lesbian, gay or bisexual were alive, compared to about 78 percent of those from high-stigma areas.

The difference translates into a shortened life expectancy of about 12 years in high-stigma communities, according to the researchers.

Heart disease, suicides, murders and violence appeared to be responsible for the shortened life expectancy.

"These are the specific causes of death that are elevated among sexual minorities living in high-prejudice communities, and they provide information on potential mechanisms or explanations for why sexual minorities living in these communities had increased risk of mortality," Hatzenbuehler said.

For example, he and his colleagues write that one possibility is that experiencing discrimination, prejudice and being marginalized creates stress. That may be an indirect way that stigma contributes to early deaths.

HIV, AIDS and behaviors such as smoking and drinking did not appear to be behind the shorter life expectancies.

What's more, the researchers found that people who reported only opposite-sex relationships also tended to have shorter lives if they lived in high-stigma communities rather than low-stigma ones.

It's too early to say why there would also be a link between stigma and life expectancy among the sexual majority, according to Hatzenbuehler.

In a separate study published in the American Journal of Public Health, Hatzenbuehler and his colleagues found that people who were straight and had high levels of anti-gay prejudice died about three years earlier than straight people without such strong anti-gay feelings.

"This adds to a very large literature that Dr. Hatzenbuehler cites in his paper that prejudice is bad for your health when you experience it," Ron Stall told Reuters Health.

Stall, who was not involved with the new study, is the director of the Center for LGBT Health Research at the University of Pittsburgh Graduate School of Public Health.

"If you buy the idea - and the evidence is getting stronger and stronger - that this kind of stigma is worsening the health of the sexual minority population, then you can think of things we can address to make it stop," Stall said.

Those include enforcing anti-bullying laws, supporting the creation of gay-straight alliance groups in schools and advocating for civil rights protections, he said.

Stall said the fight against anti-gay stigma is in the pursuit of life, liberty and happiness.

"Dr. Hatzenbuehler's paper shows it's literally in the pursuit of life," he said.

SOURCES: Social Science and Medicine, online June 18, 2013 and American Journal of Public Health, online December 12, 2013.