The trend was most pronounced among white men and women in that age group. Their suicide rate jumped 40 percent between 1999 and 2010.
But the rates in younger and older people held steady. And there was little change among middle-aged blacks, Hispanics and most other racial and ethnic groups, the report from the Centers for Disease Control and Prevention found.
Why did so many middle-aged whites — that is, those who are 35 to 64 years old — take their own lives?
One theory suggests the recession caused more emotional trauma in whites, who tend not to have the same kind of church support and extended families that blacks and Hispanics do.
The economy was in recession from the end of 2007 until mid-2009. Even well afterward, polls showed most Americans remained worried about weak hiring, a depressed housing market and other problems.
Pat Smith, violence-prevention program coordinator for the Michigan Department of Community Health, said the recession — which hit manufacturing-heavy states particularly hard — may have pushed already-troubled people over the brink. Being unable to find a job or settling for one with lower pay or prestige could add “that final weight to a whole chain of events,” she said.
Another theory notes that white baby boomers have always had higher rates of depression and suicide, and that has held true as they’ve hit middle age. During the 11-year period studied, suicide went from the eighth leading cause of death among middle-aged Americans to the fourth, behind cancer, heart disease and accidents.
“Some of us think we’re facing an upsurge as this generation moves into later life,” said Dr. Eric Caine, a suicide researcher at the University of Rochester.
One more possible contributor is the growing sale and abuse of prescription painkillers over the past decade. Some people commit suicide by overdose. In other cases, abuse of the drugs helps put people in a frame of mind to attempt suicide by other means, said Thomas Simon, one of the authors of the CDC report, which was based on death certificates.
People ages 35 to 64 account for about 57 percent of suicides in the U.S.
The report contained surprising information about how middle-aged people kill themselves: During the period studied, hangings overtook drug overdoses in that age group, becoming the No. 2 manner of suicide. But guns remained far in the lead and were the instrument of death in nearly half of all suicides among the middle-aged in 2010.
The CDC does not collect gun ownership statistics and did not look at the relationship between suicide rates and the prevalence of firearms.
For the entire U.S. population, there were 38,350 suicides in 2010, making it the nation’s 10th leading cause of death, the CDC said. The overall national suicide rate climbed from 12 suicides per 100,000 people in 1999 to 14 per 100,000 in 2010. That was a 15 percent increase.
For the middle-aged, the rate jumped from about 14 per 100,000 to nearly 18 — a 28 percent increase. Among whites in that age group, it spiked from about 16 to 22.
Suicide prevention efforts have tended to concentrate on teenagers and the elderly, but research over the past several years has begun to focus on the middle-aged. The new CDC report is being called the first to show how the trend is playing out nationally and to look in depth at the racial and geographic breakdown.
Thirty-nine out of 50 states registered a statistically significant increase in suicide rates among the middle-aged. The West and the South had the highest rates. It’s not clear why, but one factor may be cultural differences in willingness to seek help during tough times, Simon said.
Also, it may be more difficult to find counseling and mental health services in certain places, he added.
Suicides among middle-aged Native Americans and Alaska Natives climbed 65 percent, to 18.5 per 100,000. However, the overall numbers remain very small — 171 such deaths in 2010. And changes in small numbers can look unusually dramatic.
The CDC did not break out suicides of current and former military service members, a tragedy that has been getting increased attention. But a recent Department of Veterans Affairs report concluded that suicides among veterans have been relatively stable in the past decade and that veterans have been a shrinking percentage of suicides nationally.