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Autumn 2015

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blue background with light-colored veins tracing over it to show blood supply in the cerebral cortex
Brain blood supply in the cerebral cortex
 

Our understanding of the toll that diabetes, particularly type 2 diabetes, can take on brain health has gained definition following research reported by a team of scientists at HMS and Beth Israel Deaconess Medical Center. Their findings show that over a two-year period, older adults with type 2 diabetes developed complications in blood flow regulation in the brain that led to impaired memory and other cognitive problems. The research appeared online July 8 in Neurology.

Type 2 diabetes, also known as hyperglycemia, affects more than 44 million people worldwide, including 27 percent of adults over age 65. The condition develops when glucose builds up in the blood instead of entering the body’s cells to be used as energy.

The study’s findings indicated that on tests of learning and memory the scores of patients with diabetes—which started out eight points lower than scores of patients who did not have diabetes—decreased by an additional 12 percent during the two-year period. Scores of patients who did not have diabetes remained the same throughout the study. In addition, among participants with diabetes, the brain’s ability to increase blood flow when needed for mental processing or other cognitive tasks decreased by 65 percent over the study period. There was no significant change in blood flow regulation among people who did not have diabetes.

The study also showed that higher levels of inflammation were associated with greater decreases in blood flow regulation, even among the participants with diabetes who had good control of their blood sugar.

“In patients with diabetes, excess glucose appears to increase vascular inflammation and impair the endothelial cells that line blood vessels,” says Vera Novak, an HMS professor of neurology at Beth Israel Deaconess and the team’s leader. “This, in turn, impedes blood flow regulation and disrupts cognitive function.”

Adds Novak, “Our findings show that even careful glycemic control did not protect brain function in patients with type 2 diabetes. This study helps explain the mechanisms underlying long-term effects of diabetes on the brain and points to the urgent need for novel treatment strategies to prevent this effect of diabetes on brain function.”

Photo: Thomas Deerinck, NCMIR/Science Source

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Issue

Voices
Autumn 2015

Topics

neurobiology

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