Does Diabetes Increase Risk of Cognitive Decline?

There is mounting evidence that Type 2 diabetes may be associated with cognitive decline in older adults.

A new study in the July 8 online issue of Neurology found that people with Type 2 diabetes had worse regulation of blood flow to the brain over a two-year period when compared to those without the disease. This was associated with lower scores on tests of cognition skills and their ability to perform their daily activities.

“Normal blood flow regulation allows the brain to redistribute blood to areas of the brain that have increased activity 1436321382_featured.jpegwhile performing certain tasks,” said study author Vera Novak, MD, PhD, of Harvard Medical School in Boston in a statement. “People with Type 2 diabetes have impaired blood flow regulation. Our results suggest that diabetes and high blood sugar impose a chronic negative effect on cognitive and decision-making skills.”

The study involved 40 people with an average age of 66. Of those, 19 had Type 2 diabetes and 21 did not have diabetes. Those with diabetes had been treated for the disease for an average of 13 years. The participants were tested at the beginning of the study and again two years later. Tests included cognition and memory tests, MRI scans of the brain to look at brain volume and blood flow, and blood tests to measure control of blood sugar and inflammation.

Blood flow regulation in the brain decreased by 65 percent in people with diabetes. Those with lower ability to regulate blood flow at the beginning of the study had greater declines in a measure of how well they could complete daily activities such as bathing and cooking.

Higher levels of inflammation were also associated with greater decreases in blood flow regulation, even if people had good control of their diabetes and blood pressure, Novak said.

On a test of learning and memory, the scores of the people with diabetes decreased by 12 percent, from 46 points to 41 points over the two years of the study, while the scores of those without diabetes stayed the same, at 55 points. Blood flow regulation in the brain was decreased by 65 percent in people with diabetes.

“Early detection and monitoring of blood flow regulation may be an important predictor of accelerated changes in cognitive and decision-making skills,” Novak said.

Two of every three people with diabetes have high blood pressure, according to the American Diabetes Association. They are at 1.5 times higher risk of stroke and are more likely to suffer a heart attack, heart disease, kidney disease or eye problems.

Although this was a small study, its results were in line with those of previous studies, including a University of Pennsylvania investigation which found that that diabetes may actually accelerate brain aging by as much as two years. Researchers determined that those who have had the disease longer (15+ years) had less gray matter than those more recently diagnosed (four years or less).

The CDC estimates that 29 million people in the U.S. have Type 2 diabetes — including about 8 million who are unaware of their condition. Diabetes risk increases with age; more than one-quarter of those over 65 (about 10.9 million) have diabetes.

As the U.S. population continues to grow older, prevalence of chronic conditions like diabetes and its associated complications — including, apparently, cognitive impairment — will severely strain health care delivery, the long term care system, and place further stress on families caregivers.

Many chronic diseases are preventable. So put down those new Oreo thins and go take a walk.