By Jamie Talan
Monday, December 28, 1998; Page A16 Studies have linked chronic depression to heart disease and a long list of medical maladies, and now federal researchers have found a possible addition to the risk list: cancer.
Brenda Penninx and her colleagues at the National Institute on Aging have been involved in a large epidemiological study of the elderly. Within this complex database, they found that people who reported symptoms of depression each of the three times they were interviewed over a six-year period were almost twice as likely to have a subsequent diagnosis of cancer as those who were not depressed.
"These were people chronically depressed," said Penninx, a scientist from the Netherlands who works at the federal aging institute twice a year. "When you are depressed for a long period of time, it changes the chemical processes in the body."
Depression is the most common psychiatric illness, affecting 20 percent of people at some point in their lifetime. But chronic depression is less common and probably disables 3 percent to 5 percent of the population. These people experience prolonged sadness, tiredness, weight disturbances and an unrelenting hopelessness.
The federal researchers suspect that depression alters immune system functioning and that those changes can affect the growth of cancer cells. But it is too early in the investigation to really know why and how depression puts people at risk.
"These findings are intriguing and if replicated may be very important," said Martin Keller, chief of the psychiatry department at Brown University and a leading expert on chronic depression. "If people with chronic depression are getting cancer at a higher rate, the public health implications are enormous. But it requires a lot more investigation."
The researchers studied 5,000 elderly people in four communities throughout the United States. From 1982 to 1988, scientists conducted personal interviews and administered screening questionnaires designed to pick up depression. Three percent of those interviewed had signs of moderate to severe depression throughout the six-year testing period.
In 1992 the researchers pored over the previous four years of a hospital database at the Health Care Financing Administration, the federal agency that runs the Medicare and Medicaid programs, to see who among the chronically depressed patients had undergone any treatment for cancer. They also looked at a group of people who scored high on the depression survey in 1988, but not on the two previous surveys.
Finally, they selected a control group of people who did not show any signs of cancer during the six-year period.
Penninx and her colleagues found that people with chronic depression had almost twice the rate of cancer as those with acute depression or no depression. The finding was still solid after the investigators accounted for any history of smoking, drinking and use of antidepressant drugs. None of the 5,000 people studied had any evidence of cancer when they entered the study in 1982. The types of cancers identified subsequently were varied, but the most common was uterine cancer.
The study was published in the current issue of the Journal of the National Cancer Institute.
NIA epidemiologist Richard J. Havlik, one of the study investigators, said there could be other reasons for the association. During the study, researchers did not have information on the use of estrogens and stress hormones that could have put people at increased risk for cancer. Nor did they look at a person's social support network, a lack of which also has been associated with an increased risk of medical problems.
The study "is provocative and interesting but should be replicated in
younger people," Havlik said. "A lot of people are intrigued by the
mind-body connection in cancer."
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