Depression Can Forewarn of Alzheimer's Disease

Mind-robbing illness can appear years later

Edward Edelson

Edward Edelson

Published on May 19, 2003

MONDAY, May 19, 2003 (HealthDayNews) -- Depression in the early years of life can be a warning sign that Alzheimer's disease will develop decades later, new research claims.

That finding is not astoundingly new, says Dr. Robert C. Green, an associate professor of neurology at Boston University School of Medicine who reports it in the May issue of the Archives of Neurology. However, it comes from a study that is much larger than earlier trials that found a similar link, and it confirms the need to find out why that link exists, he says.

"Does Alzheimer's disease start in a very subtle way in the 20s or 30s?" he asks. "Or could it be that people who are less prone to depression have more resistance to getting Alzheimer's disease? Or is there something about depression that is somehow toxic to the brain?"

All those questions remain unanswered, Green says. The real importance of the study, he says, is that it adds to a mosaic of possible risk factors that someday could be used to identify people at high risk of the mind-robbing condition who could be treated -- when treatments become available.

This study included 1,953 people with Alzheimer's disease who were matched with 2,093 of their close relatives who did not have the disease. The incidence of depression was found by questioning those relatives.

Overall, people with a history of depression symptoms were twice as likely to have Alzheimer's, the researchers report. If depression began a year before the onset of Alzheimer's, the association was almost five times stronger. And the incidence of Alzheimer's was 70 percent greater even if depression was reported to have begun more than two decades earlier.

Those numbers must be viewed with caution, says Jennie Ward-Robinson, director of medical and scientific affairs at the Alzheimer's Association. "They depend on recollection by caregivers, and those recollections are complicated by the relationship of the caregiver to the patient," she says.

But she agrees with Green on one point: "What is exciting is that we are beginning to learn more about Alzheimer's disease and are getting to the point where we can talk in terms of risk factors."

Head injuries increase the risk, Green explains, while taking antidepressants, vitamin E or statins -- cholesterol-lowering drugs -- appears to reduce the risk.

"The importance of this paper is not so much the individual finding as that it helps create profiles of people at higher and lower risk, and of protective factors," he says.

Already, there are tentative efforts to put some of that information to use, Ward-Robinson says, most notably in trials looking at the relationship of statin therapy to Alzheimer's disease.

"We are converging on a picture that will help us better understand the mechanistic process of Alzheimer's disease," Green says.

More information

The Alzheimer's Association monitors new developments in the fight against the disease. And read more about other possible causes of Alzheimer's.

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