Study: Diabetes Has Negative Long-Term Effect on Cognitive Skills

New research suggests that type 2 diabetes has negative long-term effects on thinking and memory. People with diabetes had decreases in their ability to regulate cerebral blood flow after just 2 years and also had lower scores on tests of cognitive skills and their ability to perform their daily activities, according to the recent study.

“People with type 2 diabetes have impaired blood flow regulation,” said study author Vera Novak, MD, PhD, of Harvard Medical School in Boston. “Our results suggest that diabetes and high blood sugar impose a chronic negative effect on cognitive and decision-making skills.”
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Novak and her colleagues conducted a 2-year study that involved 40 participants—19 with type 2 diabetes and 21 who did not have diabetes. The average age of the study subjects was 66, and those with diabetes had been treated for an average of 13 years.

At enrollment and 2 years later, researchers administered cognition and memory tests, MRI scans of the brain to measure brain volume and blood flow, and blood tests to determine inflammation and blood glucose levels.

The 2-year follow-up testing showed that cerebral blood flow regulation had decreased by 65% in the group with type 2 diabetes. Their learning and memory test scores had also declined by 12%, while the control group’s scores stayed the same.

Those who had a lower ability to regulate blood flow at the start of the study showed a more significant decline in a measure of their ability to complete daily living tasks, such as bathing and cooking.

The researchers also found that higher levels of inflammation were associated with greater decreases in blood flow regulation, even in those who had good control of their diabetes and blood pressure.

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

Novak and her colleagues concluded that a study with a larger sample size and longer follow-up period is warranted to develop a better understanding of the time sequence of the relationship between blood flow regulation and changes in thinking and memory skills in type 2 diabetes.

—Colleen Mullarkey

Reference

Chung C, Pimentel D, Jor’dan AJ, Hao Y, Milberg W, Novak V. Inflammation-associated declines in cerebral vasoreactivity and cognition in type 2 diabetes. Neurology. 8 July 2015. [Epub ahead of print].