Suicide rates for middle-aged people are edging up – particularly for white men without college degrees – and a combination of poor health and a poor economy may be driving it, U.S. researchers said on Monday.

Middle-aged people usually have a relatively low risk for suicide as they seek to support their families, but baby boomers are bucking this trend, sociologists Julie Phillips of Rutgers University in New Jersey and Ellen Idler of Emory University in Atlanta found.

"If these trends continue, they are cause for concern," Phillips and Idler wrote in the journal Public Health Reports.

"Male baby boomers have yet to reach old age, the period of the male life course at highest risk for suicide; if they continue to set historically high suicide rates as they did in adolescence and now in middle age, their rates in old age could be very high indeed."

The researchers used suicide data from the National Center for Health Statistics and analyzed it by age group, marital status, education and other factors. The period they studied preceded the most recent economic crisis.

"Following a period of stability or decline, suicide rates have climbed since 1988 for males aged 40-49 years, and since 1999 for females aged 40-59 years and males aged 50-59 years," they wrote.

In 1979 the suicide rate for men aged 40 to 49 was 21.8 per 100,000. It rose to as high as 24 per 100,000 in 1996 and to 25 by 2005. For men 50 to 59 it was 23.9 in 1979, fell to 20.4 per 100,000 in 1999 and rose again to nearly 23.8 in 2005.

For women it was much lower – 9.9 in 1979 for women aged 40 to 49, rising and falling during the years in between and ending at 7.8 per 100,000 in 2005.

"One question we asked was does this have something to do with the people?" Phillips said in a telephone interview. "Baby boomers have been a group noted for high rates of suicide in the past. It makes me wonder if there is something about baby boomers that may contribute to this pattern."

To figure out what might be causing the changes, Idler and Phillips looked at potential outside factors – although they note that just because two things happen at the same time, it does not prove cause and effect.

"Unemployment rates in the U.S. rose between 2000 and 2003 at the same time that middle-aged suicide rates increased rapidly," they wrote.

"In addition, rates of bankruptcy increased between 1991 and 2007, in part because of changes in the law, but with personal financial consequences nevertheless."

And baby boomers are the least healthy middle-aged generation, with large rates of obesity and the diseases that result, such as diabetes and heart disease.

"The percentage of those aged 45 to 64 years with multiple chronic diseases increased from 13 percent in 1996 to 22 percent in 2005, with a concomitant rise in out-of-pocket spending for health-care services," Phillips and Idler wrote.

"The burden of disease falls disproportionately on those who are less educated, the group also least likely to have adequate employer-based health insurance."

As other studies have shown, the risk of suicide was substantially larger for unmarried than for married people, with unmarried middle-aged men 3.5 times as likely to commit suicide as married middle-aged men.