How Diabetes Harms the Brain
Diabetes can damage a number of organs, from the eyes to the kidneys and the heart. Now there’s fresh evidence that unchecked blood sugar can affect the brain as well, which may lead to drops in cognitive functions
When blood sugar levels start to climb in diabetes, a number of body systems are harmed—and that list includes the brain, since studies have linked diabetes with a higher risk of stroke and dementia. Now, a new study published in the journal Neurology reports that changes in blood vessel activity in the brains of diabetics may lead to drops in cognitive functions and their ability to perform daily activities.
Dr. Vera Novak, associate professor of neurology at Harvard Medical School and Beth Israel Deaconess Medical Center, and her colleagues followed a group of 65 older people. About half had type 2 diabetes, and half did not. After two years, the diabetic patients had lower scores on cognitive tests compared to when they began, while people without diabetes showed little change on the tests.
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What drove the decline, says Novak, were changes in the brains of the diabetic patients. Diabetes can cause blood vessels to be less responsive to the ebb and flow of demand in different parts of the brain. Normally, flexible vessels will swell slightly to increase blood flow and oxygen to areas that are more intensely active, such as regions involved in memory or higher reasoning during intellectual tasks. But unchecked blood sugar can make these vessels less malleable and therefore less responsive.
“When doing any task, from cognition to moving your fingers, you need to increase blood flow to that specific area of the brain,” says Novak. “With diabetes, however, that vasodilation ability is reduced, so you have fewer resources to perform any task.”