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Depression Linked to Alzheimer's Disease

Study Shows Depression in Elderly Doubles Dementia Risk
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WebMD Health News
Reviewed by Louise Chang, MD

July 6, 2010 -- Older people who suffer from depression have nearly double the risk for developing Alzheimer’s disease and dementia, a new study finds.

Researchers followed elderly participants in the ongoing Framingham Heart Study for up to 17 years to explore late-life depression and dementia.

They found depression to be a significant risk factor for dementia, even after other suspected contributors to dementia and Alzheimer’s disease had been considered.

But it is not clear if depression is a risk factor for dementia or if vulnerability to depression also makes people more vulnerable to Alzheimer’s disease.

Previous studies examining the impact of late-life depression on dementia have been mixed, possibly because participants were not followed long enough, study researcher Jane Saczynski, PhD, of the University of Massachusetts Medical School tells WebMD.

“A major criticism of many of the earlier studies was that the interval between the measurement of depression and dementia was not long enough,” she says. “In our study, people were followed for up to 17 years and the assessment of dementia was very, very rigorous.”

Depression, Dementia Common

As many as 6 million Americans ages 65 and older suffer from depression, but only about one in 10 receives treatment because depression is often not recognized or is wrongly considered a normal part of aging.

Depression can also lead to memory and other cognitive impairments in older people, complicating the diagnosis of both disorders.

The newly published study included 947 longtime participants in the Framingham Heart Study, which has followed residents of Framingham, Mass., since the late 1940s.

All were elderly but showed no signs of dementia when enrolled in the study. Their average age at enrollment was 79, and 125 (13%) were classified as having depression at the start of the study.

By the end of follow-up, 164 people had developed dementia, including 136 with a specific diagnosis of Alzheimer’s disease. Those with a diagnosis of depression at the start of follow-up had a 70% greater risk for developing dementia.

Roughly one in three people with depressive symptoms at the start of the study developed dementia compared to one in five people without a diagnosis of depression.

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