A small study suggests that type 2 diabetes can trigger observable declines in cognitive ability within as narrow a time frame as 2 years.
The authors, led by Vera Novak at the Beth Israel Deaconess Medical Center (Boston, MA, USA), followed 65 people with a mean age of 66 years, of whom approximately half had type 2 diabetes. After 2 years, whereas people without diabetes had no significant decline in cognitive function, those with the condition had a 12% reduction in executive function and memory test scores.
These differences were attributed to increased tissue inflammation and reduced cerebral blood flow in the people with type 2 diabetes. This group had a 65% reduction in blood flow regulation and a 50% decline in cerebral vasoreactivity. Lower cerebral vasoreactivity was associated with a greater reduction in activities of daily living scores (r2=0.35; P=0.04), and lower systemic vasodilation was associated with a greater decline in executive function (r2=0.6; P=0.047). The levels of inflammation markers, including cortisol and C-reactive protein, were associated with greater reductions in cerebral vasoreactivity and vasodilation, independently of glycaemic control and blood pressure, and higher HbA1c levels were associated with increased vasoconstriction.
Commenting on the study, Dr Novak said: “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. Early detection and monitoring of blood flow regulation may be an important predictor of accelerated changes in cognitive and decision-making skills.”
Although this was a small study that requires validation in larger cohorts, the findings add to the evidence of a link between diabetes and cognitive decline, and they provide a number of biomarkers that can be tracked prospectively even over a relatively short period of time.
The study can be read in Neurology here.
