A large body of research has linked late-life dpression to social isolation, poorer heatlh and an increased risk of death. Now, a new study finds that depression is associated wtih subsequent vascular dementia and Alzheimer's disease, conditions poised to expand dramatically with the aging population.
The report, published on Wednesday in the British Journal of Psychiatry, is a meta-analysis of 23 previous studies that followed nearly 50,000 older adults over a median of five years. The researchers found that depressed older adults (defined as those over age 50) were more than twice as likely to develop vascular dementia and 65 percent more likely to develop Alzheimer's disease than similarly aged people who weren't depressed.
"We can't say that late-life depression causes dementia, but we can say that it likely contributes to it," said Meryl Butters, an associate professor of psychiatry at the University of Pittsburge School of Medicine and a co-author of the paper. "We think depression is toxic to the brain, and if you're walking around with some mild brain damage, it will add to the degenerative process."
In terms of absolute risk, she said, the data suggest that 36 of every 50 older adults with late-life depression may go on to develop vascular dementia, while 31 of every 50 seniors with a history of depression may eventually be diagnosed with Alzheimer's.