Reason to be Happy
Chronic depression may rob you of more than joy: the evidence is piling up that it can also steal your health
Bryce Miller's work as an industrial engineer in Topeka, Kan., wasn't a whole lot more challenging than the job he faces in retirement: engineering his own medical care by 10 different doctors. Miller, 74, sees a team of specialists, which includes a cardiologist, a urologist and radiologist for prostate cancer, an endocrinologist for diabetes, a nephrologist for kidney problems, and a psychiatrist to manage the severe episodes of depression he has suffered during a long struggle with bipolar disorder. "I can't find a doctor who can handle all of it," he says.
It's impossible to pinpoint all the causes of Miller's illness; a combination of bad genes, bad luck, and bad diet probably gets much of the blame. But lately, he says, he's been wondering whether his mental state may have played a role, too. Medicine has recognized for some time that chronically sick people are prone to depression and that those affected have a tougher road back. Now, the signs are mounting that the spectrum of depressive illness, and perhaps even bitter loneliness, may actually make healthy people more vulnerable to a range of physical ailments. "There is a growing body of evidence suggesting that depression might be a causal risk factor in diseases like ischemic heart disease, stroke, diabetes, and immune-based diseases like cancer and HIV/AIDS," says Dwight Evans, chair of psychiatry at the University of Pennsylvania medical school. "And there is also considerable recent evidence that mood disorders can affect the course of medical illnesses. It goes both ways. Depression may be both a cause and a consequence of medical illness."
Risk factor. Consider a study published last month in the journal Diabetologia, which concluded that depressed adults have a 37 percent greater risk of developing type 2 diabetes than the rest of the population; other studies have suggested their risk actually doubles. (Apparently, English physician Thomas Willis was on to something when he wrote in 1674, "Diabetes is caused by melancholy.") One intriguing recent study of Alzheimer's patients revealed that those with a history of depression had more extensive plaques in their brains. Depressed postmenopausal women with no history of heart disease are much more likely to develop it and die of it than their peers. In March, University of Chicago researchers showed that loneliness can spike blood pressure by 30 points in older people. Pancreatic cancer, for reasons scientists don't understand, is often preceded by a serious depression before the disease asserts itself.
And when melancholy comes on the heels of disease, it appears to compound the physical insult. Diabetes is more likely to be uncontrolled, for example. And several studies have found that in the months right after a heart attack, the depressed patients are much more likely to die than the others.
If the researchers are right, the human cost of letting depression go untreated is staggering. Nearly 25 percent of American women and 10 percent of men will be clinically depressed at some point in their lives; a massive study conducted by the World Health Organization, Harvard University School of Public Health, and the World Bank found that by 2020, depression will be second only to heart disease as a cause of medical and physical disability. People who have suffered silently because their mental-health insurance benefits are so stingy got a glimmer of hope last week from the results of a large study showing that employers could beef up benefits without significantly raising costs (Box, below).