After falling for more than a decade, the U.S. suicide rate has climbed steadily since 1999, driven by an alarming increase among middle-aged adults, researchers said yesterday.
A new six-year analysis in the American Journal of Preventive Medicine found that U.S. suicide rate rose to 11 per 100,000 in 2005 from 10.5 per 100,000 in 1999, an increase of just under 5 percent.
The report found that virtually all of the increase was attributable to a nearly 16 percent jump in suicides among people ages 40 to 64, a group not commonly seen as high risk. The rate for that age group rose to 15.6 per 100,000 in 2005 from 13.5 per 100,000 in 1999.
Susan P. Baker, an epidemiologist at Johns Hopkins University Bloomberg School of Public Health and a study author, said she was baffled by the findings. Sociological studies have found that middle age is generally a time of relative security and emotional well-being, she said.
"We really don't know what is causing this," said Dr. Paula Clayton, research director of the American Foundation for Suicide Prevention, who was not involved in the study. "All we have is speculation."
One possibility, she said, is that the increase in suicides might be tied to a concurrent increase in abuse of prescription pain pills, such as OxyContin. Studies have shown that people who abuse drugs are at greater risk for suicide, she said.
Another possible explanation, she said, was the drop in hormone-replacement therapy after it was linked to health risks in 2002. Women who gave up the drugs or decided not to take them might have been more susceptible to depression and, potentially, suicide, she said.