Older Diabetics Suffer Greater Cognitive Impairment, Brain Volume Loss

Diabetes in older patients leads to memory loss, depression and other types of cognitive impairment, according to a five-year study published in the November 2011 issue of Diabetes Care. The study also found a higher rate of brain volume loss in older diabetics than older non-diabetics.

Researchers found more inflammation in the brain in older diabetics than in non-diabetics in the study. This inflammation causes greater blood vessel constriction, which leads to brain tissue atrophy.

“Once chronic inflammation sets in, blood vessels constrict, blood flow is reduced, and brain tissue is damaged,” says Vera Novak, MD, PhD at Beth Israel Deaconess Medical Center and lead researcher of the study.

Researchers also identified the two biomarkers causing these serious consequences in older diabetics. They discovered the presence of two adhesion molecules—sVCAM and sICAM—that alter vascular reactivity and inflammation in the brain.

Inflammation of the blood vessels often occurs alongside hyperglycemia, the build up of glucose in the blood. Novak's team studied 147 participants averaging 65 years of age to see if this chronic inflammation was causing altered flood flow to the brain.

MRI brain scans confirmed that the type-2 diabetic participants suffered greater blood vessel constriction than the non-diabetic control subjects. They showed more atrophied brain tissue, especially gray matter, in the frontal, temporal and parietal brain regions. Those areas are responsible for decision-making, language, verbal memory and complex tasks.

In addition, serum samples from the study confirmed that high glucose levels are significantly linked to higher levels of inflammatory cytokines. Cytokines are small proteins that serve as messengers between cells and regulate various inflammatory responses.

“It appears that chronic hyperglycemia and insulin resistance—the hallmarks of diabetes—trigger the release of adhesion molecules [sVCAM and sICAM] and set off a cascade of events leading to the development of chronic inflammation,” said Novak.

Novak's previous research found that at age 65 years, the average person's brain shrinks about one percent a year. A diabetic person's brain can shrink by as much as 15 percent a year.

“Cognitive decline affects a person's ability to successfully complete even the simplest of everyday tasks, such as walking, talking or writing,” said Novak. “The effects of diabetes on the brain have been grossly neglected, and, as our findings confirms, are issues that need to be addressed.”

Source: Beth Israel Deaconess Medical Center