NEW YORK - Inflammation may contribute to impaired cerebral vasoregulation in type 2 diabetes, research suggests.
In a two-year study, participants with type 2 diabetes experienced diminished regional and global vasoreactivity in the brain, as well as a decline in cognitive function and the ability to perform daily tasks.
Higher blood levels of inflammatory markers were correlated with decreases in cerebral vasoreactivity and vasodilation in the diabetic subjects, but not in controls.
"Normal blood flow regulation allows the brain to redistribute blood to areas of the brain that have increased activity while performing certain tasks," senior author Dr. Vera Novak, of Beth Israel Deaconess Medical Center in Boston, said in a news release. "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's final analysis involved 40 people, average age 69, including 19 with diabetes and 21 controls. The diabetes patients had been treated for the disease an average of 13 years. Smokers were excluded.
The researchers administered a number of cognition and memory tests, magnetic resonance imaging (MRI) scans and blood tests at the beginning of the study and at 24 months.
At the two-year visit, the diabetics had lower global gray matter volume, lower composite scores on learning and memory, lower regional and global cerebral vasoreactivity, and worse glycemic control, compared to baseline.
Among the diabetics, impaired cerebral vasoreactivity at baseline correlated with worse performance of daily activities. In addition, worsening vasodilation correlated with greater decreases in executive function, independent of age, education, and other factors.
"Higher serum soluble intercellular and vascular adhesion molecules, higher cortisol, and higher C-reactive protein levels at baseline were associated with greater decreases in cerebral vasoreactivity and vasodilation only in the (diabetes) group, independent of diabetes control and 24-hour blood pressure," the researchers wrote online July 8 in Neurology.
"Inflammation may further impair cerebral vasoregulation, which consequently accelerates decline in executive function and daily activities performance in older people with (diabetes)," they said.
"Early detection and monitoring of blood flow regulation may be an important predictor of accelerated changes in cognitive and decision-making skills," Dr. Novak said in the news release. She called for additional studies in a greater number of people and for a longer duration.
"We are currently starting a Phase 2-3 clinical trial to see if intranasal insulin could prevent/slow down cognitive decline," she told Reuters Health by email.
She also noted that while no specific treatment exists to prevent cognitive decline, healthy life styles help people to have less decline.
Large clinical trials have shown that even strict control of blood sugar does not prevent cognitive decline. The high fluctuation in blood glucose that occurs with diabetes damages the nerves of the brain, she said.
The study was funded by the National Institute on Aging, American Diabetes Association, Harvard Clinical and Translational Science Center and National Center for Research Resources.