Diabetes and depression increase dementia risk
Depression and diabetes on their own can affect the brain, but together they can significantly increase the risk of dementia, a new study found.
Dementia is an umbrella term for a decline in mental ability that is severe enough interfere with daily life. Alzheimer’s disease is the most common form of dementia, and accounts for 60 to 80 percent of dementia cases.
Dr. Dimitry Davydow, an associate professor of psychiatry and behavioral sciences at the University of Washington School of Medicine and his team examined dementia risk among over 2.4 million adults age 50 and older in Denmark who had depression (19.4 percent), type 2 diabetes (9.1 percent) or both (3.9 percent), and compared them with people who didn’t have either condition.
All of the subjects were dementia-free at the beginning of the study, but during 13,834,645 person-years of follow-up, 2.4 developed dementia. Of those, 10.8 percent had type 2 diabetes, 26.4 percent had depression, and 6.7 percent had both.
“What this argues for is, we need to do a better job of both identifying diabetes and depression and then really treating them once identified,” Dr. Davydow said. “Even after taking those into account, diabetes itself raised the risk of dementia by 15 percent, depression by 83 percent and the two together by 107 percent.”
Davydow also said that the association between having both depression and type 2 diabetes was especially strong in people younger than 65. “A quarter of the cases were attributed to depression and diabetes,” he said. He also said that to his and his team’s knowledge, their study was the first to look at the association between diabetes, depression and dementia.
Although the study establishes a link between depression, diabetes and dementia, it does not establish a direct cause-and-effect relationship. However, Davydow said that diabetes makes it more likely that plaque will develop in the blood vessels, which can then lead to strokes and dementia.
The study was published April 15 in JAMA Psychiatry.
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