Suicide rates among middle-age people are going up, according to a new study. The trend seems to be driven by the entrance of the Baby Boom generation into middle age, when chronic diseases rear their ugly heads.

The study, published in the journal Public Health Reports, reveals middle-age suicides to be at odds with the overall U.S. suicide rate, which has been declining. People ages 40 to 59 have long had a moderate suicide rate, according to sociologist Ellen Idler of Emory University in Atlanta, who co-authored the research paper.

“The findings are disturbing, because they’re a reversal of a long-standing trend,” Idler said in a statement.

Using data from the National Center for Health Statistics and the U.S. Census Bureau, Idler and her colleagues tracked suicide rates between 1979 and 2005. By 2000, most people ages 40 to 59 were Baby Boomers and the suicide rate started climbing steadily for these middle-age ranges. The researchers found significant increases of more than 2 percent per year for men, and more than 3 percent per year for women, from 1999 to 2005. (By 2005, all those in the middle-age group were baby boomers, defined as those born between 1945 and 1964.)

Preliminary data from 2006 and 2007, the latest years for which numbers are available, indicate that the trend toward more middle-age suicides is continuing, Idler said. According to the National Center for Health Statistics, the suicide rate for 45- to 54-year-olds was 17.7 deaths per 100,000 people in 2007. That's compared with 13 deaths per 100,000 people in the 25- to 34-year-old age group and 12.6 deaths per 100,000 in the 65- to 74-year-old group.

Though many are surprised to learn it, suicide claims more lives than homicide, and that’s long been true.

The post-1999 increase in middle-age suicide has been particularly dramatic for those who are unmarried and less educated, the analysis showed. Suicide rates in men aged 40 to 49 who had some college but no degree went up 16.3 percent between 2000 and 2005, while the suicide rate in men aged 50 to 59 went up 29.6 percent. Women showed a similar pattern, with about a 30 percent increase in the suicide rate for women with some college but no degree in both age groups.

Men and women with a high school degree or less also became more likely to commit suicide. Rates in men with a high school diploma went up 11.7 percent in the 40 to 49 age group and 27 percent in the 50 to 59 age group. Women in those groups saw their suicide rates increase by 15 and 17 percent, respectively.  Middle-age participants with a college degree appeared largely protected from the trend.

The baby boomers also experienced higher suicide rates during their adolescence and young adulthood, doubling the rate for those age groups at the time. Their suicide rate then declined slightly and stabilized, before beginning to increase again in midlife.

“You might think that the higher rates in adolescence would lead to lower rates later because the most suicide prone people would be gone, but that doesn’t appear to be the case,” Idler said.

Studies show that knowing someone who committed suicide is a risk factor for people who later kill themselves.

"The high rates in adolescence could actually be contributing to the high rates in middle age," Idler said.

Idler also said substance abuse and the onset of chronic disease could contribute to baby boomer suicides.

“As children, the baby boomers were the healthiest cohort that had ever lived, due to the availability of antibiotics and vaccines,” she said. “Chronic conditions could be more of a rude awakening for them in midlife than they were for earlier generations.”