LAWRENCE — U.S. adults 50 and older who suffer from major depression face a 43 percent increase in the risk of death, especially cardiovascular disease or cancer, according to a study involving a University of Kansas researcher published recently in the Journals of Gerontology: Social Sciences by Oxford University Press.
"There's a major link between major depression and mortality. Taking all these other health behaviors out of it, you can continue to find this unique relationship between depression and mortality," said Jarron M. Saint Onge, a KU assistant professor of sociology and the study's lead author. "There's something that's leading to early death. And that's taking out smoking, taking out exercise, all these behavioral factors that would explain it."
Saint Onge said the study's findings are significant because they suggest that the relationship between depression and mortality is not due solely to people smoking or exhibiting unhealthy behaviors or experiencing chronic conditions that contribute to a higher risk of mortality.
When the researchers adjusted for factors such as marital status, education, employment status, family income, alcohol consumption, level of physical activity, smoking status, body mass, functional limitations and chronic conditions, they still found an independent association among major depression and increased risk of non-suicide mortality among the age group.
This includes findings that major depression was associated with 2.68 times the risk of cardiovascular disease mortality among those who did not have cardiovascular disease at the baseline.
"What we're finding here is it's important to be vigilant to find depression among people older than 50 because of a host of reasons," Saint Onge said. "It's important because of its relationship with health-compromising behaviors, but it's also important because it stands as an independent risk factor in mortality. There might be something unique about depression, taking aside all of your other behaviors, that there's something about depression that might lead to an increased risk of mortality."
He said related research has suggested major depression may have a physiological effect on blood pressure or arterial tightening that can cause cardiovascular disease.
"It's physiologically important, but it's also socially important to think of depression as a risk factor for death as well," he said.
Saint Onge, who also serves in the University of Kansas Medical Center's Department of Health Policy within the School of Medicine, co-authored the study with Patrick M. Krueger, an assistant professor of sociology at the University of Colorado at Denver, and Richard G. Rogers, a professor of sociology at the University of Colorado at Boulder.
For the mortality data, researchers examined the 1999 National Health Interview Study linked to the 2006 National Death Index, which included a sample size of 11,369 adults respondents ages 50 and older, of whom 2,162 have died from non-suicide or accident related deaths. To measure major depression, they used data derived from the World Health Organization's Composite International Diagnostic Interview Short-Form, or CIDI-SF, which is generally accepted as an accurate measure of major depression.
Saint Onge said he hoped the study would bring awareness to the issue of major depression among people older than 50. For example, white men older than 65 represent a group with one of the highest suicide rates. He said increased vigilance in recognizing the problem and coming up with better coping mechanisms to help adults deal with depression in a healthy way would be key.
"We are always thinking of 20 year olds with depression because there are highly publicized suicide rates among 20 year olds," Saint Onge said. "But increasing rates of depression among the elderly pose continued health risks, beyond suicide”
He said people who suffer from major depression often turn to unhealthy habits — like smoking or binge drinking — in addition to social withdrawal and disobeying doctors' recommendations for treatment that lead to long-term health problems. It also could help, he said, to promote treatment of depression and healthy habits among younger people before they reach the age of 50, because it can be more daunting for people of older ages to start exercising, for example, if they haven't done it much in their lives before.
"It's related to health behaviors and that you continue to see that risk of mortality goes down once you start accounting for some of these health behaviors," Saint Onge said. "When we think about that, it just suggests how important it is to focus in on behaviors like physical activity, especially among people who are depressed."
Grants from the National Institute on Aging and through the Eunice Kennedy Shriver National Institute of Child Health and Human Development-funded University of Colorado Population Center supported the research project.