Type 2 diabetes with depression boosts risk of dementia

April 16--It's already known that people with Type 2 diabetes and those with depression each face a greater risk of dementia.

But now a study published online Wednesday in JAMA Psychiatry says people with both conditions face a risk of dementia higher than expected.

"Depression and diabetes mellitus were independently associated with a greater risk for dementia, and the combined association of both exposures with the risk for all-cause dementia was stronger than the additive association," the study concludes.

Type 2 diabetes and depression go hand-in-hand. Poorly managed blood-glucose levels can lead to depression while inactivity from depression raises the risk of diabetes. Type 2 diabetes brings a 20 percent higher risk of dementia as compared with people without diabetes due to "poorer adherence to diet, smoking cessation, exercise and medication regimens" necessary for control, the study says. Depression is associated with an 83 percent higher risk of dementia.

For years, researchers followed 2.5 million Danes, age 50 and older, including 477,133 with depression and 223,174 with Type 2 diabetes. It found that people younger than 65 with both diabetes and depression represented 25 percent of all dementia cases in that age group. Six percent of all dementia cases among people 65 and older had both conditions.

The big message is that "the best treatment for dementia is preventing it from happening," said Dimitry Davydow, University of Washington associate professor of psychiatry, adding that no treatment can reverse dementia.

Most dementia cases combine Alzheimer's disease and vascular dementia caused by strokes or other interruptions of blood flow to the brain. Dementia results in "significantly impaired intellectual functioning that interferes with normal activities and relationships," the National Institutes of Health states. People with dementia also "lose their ability to solve problems and maintain emotional control, and they may experience personality changes and behavioral problems, such as agitation, delusions and hallucinations."

"We found that depression and diabetes mellitus were both associated with a greater risk for all-cause dementia, Alzheimer's disease and vascular dementia," the study states.

In his commentary published alongside the study, UPMC geriatric psychiatrist Charles F. Reynolds III said study results are plausible and stress the need for lifestyle interventions to coach people about healthy dietary practices, with the need for drug targets to improve human health. In all, he said, we need "convergent scientific approaches to meet the challenge of promoting healthy brain aging and cognitive fitness into the last years of life."

David Templeton: dtempleton@post-gazette.com or 412-263-1578.

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