February 2, 2006

Study confirms physical toll of stressful events

Univ. of Mich.

ANN ARBOR, Mich. — The death of a child. Divorce. An assault. Loss of a job. These and other highly stressful events can take a toll on physical health and mortality many years later, according to a University of Michigan study published in the current issue of the Journal of Health and Social Behavior. And life-altering events like these are especially likely to happen to people with low levels of education and income, the study found.

Overall, the study found that nearly half of a nationally representative sample of 3,617 U.S. adults had experienced at least one of four major life stresses at the start of the study. About 12 percent had been widowed, 25 percent had been divorced, 11 percent had lost a child and about 16 percent had been the victim of a serious physical assault.

They found that the more negative events people experienced, the higher their risk of death. Considering many other factors, those experiencing more of these serious life events had a 25 percent higher mortality rate over the next eight years.

The findings are among the first from longitudinal studies to support the popular belief that "allostatic load"—the cumulative impact of stress from personal loss and bad luck—takes a toll on health and mortality. The study, funded by a grant from the National Institute on Aging, followed the same people over a period of eight years.

"We expected to find socioeconomic differences in the prevalence of many stressful events," said Paula Lantz, the U-M researcher who was lead author of the study. "But the magnitude of many of these differences was surprising."

For example, among those ages 25 to 44, about 11 percent of those without a high school diploma had a child who died, compared with just 1 percent of those with a college degree. Among middle-aged adults, the percentages were higher but the pattern was the same. About 23 percent of those with the least education had a child who died, compared with 6.5 percent of the most educated.

Other notable differences:

• About 16 percent of middle-aged people without a high school degree had been widowed, compared with only 6 percent of the most educated.

• About 31 percent of the least educated young adults had been physically assaulted, compared with 17 percent of the most educated.

"By the time people reach the age of 65, the differences are not as pronounced," Lantz said. "At that stage of life, bad things like the death of a child or the loss of a spouse have unfortunately caught up with more people at all levels of income and education."

The study also measured three main types of chronic stress: financial, marital and parental stress. It found that significant socioeconomic differences in these types of stress—especially financial stress—contributed to large disparities in health status and mortality over time. Taken together, the results support the belief that differential exposure to stress and negative life events helps produce socioeconomic inequalities in health.

"The chances that bad things will happen to people are strongly related to their income and education levels," Lantz said, "and the impact of these negative events, along with the wear-and-tear of chronic financial and parental stress, translate into poorer health and greater mortality for millions of Americans."