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Depression Linked to Alzheimer's Disease

Study Shows Depression in Elderly Doubles Dementia Risk

3 Studies Show Depression, Dementia Link

The study was one of three published in the July 6 issue of Neurology, suggesting a link between late-life depression and dementia.

In a separate study that included just over 1,200 older participants, having two or more episodes of depression late in life doubled the risk of dementia, but not a lesser form of cognitive decline known as mild cognitive impairment.

In a third study, symptoms of depression showed little change during the development and progression of Alzheimer’s disease.

“The association between depression and dementia has been a major topic for more than two decades, and it is increasingly clear this association is real,” Alzheimer’s researcher Yonas E. Geda, MD, tells WebMD.

Geda is an associate professor of neurology and psychiatry at the Mayo Clinic College of Medicine in Rochester, Minn.

In an editorial published with the studies, Geda suggested several possible explanations for the observed link between late-life depression and dementia, including:

  • Major depression may directly damage the part of the brain associated with learning and memory via inflammation or the release of stress hormones.
  • Depression may be in response to early, but medically unrecognized, memory declines.
  • Depression may act synergistically with biological factors that have been linked to dementia to cause cognitive decline.
  • The same biological factors that lead to depression late in life also lead to dementia.

A major brain imaging study known as the Alzheimer’s Disease Neuroimaging Initiative may lead to new insights into the association between depression and dementia, Geda says.

If depression is a direct risk factor for dementia, treating more elderly people for depression could have a big impact, Saczynski adds.

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