Mild cognitive decline is a natural and inevitable part of growing older. Unfortunately, for people with diabetes, the disease can accelerate this process. Diabetes can hamper blood circulation and weaken the small vessels in the brain, causing tissue damage and affecting mental functions needed for day-to-day tasks -- including those essential to healthy diabetes management. This can prompt a vicious cycle of reduced cognitive function and worsening blood-sugar control, and potentially lead to the development of serious conditions such as dementia, Alzheimer's or stroke.
Elderly people are at high-risk to entering this cycle, as they are especially sensitive to the effects of high blood-sugar levels on the brain. While the impact of diabetes on brain function is complex and poorly understood, Vera Novak, MD, PhD, from the Beth Israel Deaconess Medical Center, has made novel clinical breakthroughs in this field of medicine through two American Diabetes Association-supported research projects. She has established strong links between diabetes, inflammation and blood flow within the brain. Furthermore, she has confirmed the correlation between the hallmarks of type 2 diabetes, brain atrophy and cognitive decline in aging adults.
In a recent study published in the November 2011 issue of Diabetes Care, Dr. Novak identified a critical mechanism and two key molecules in the brain that are triggered by long-term elevation of blood-sugar levels and insulin resistance. This induces an inflammatory response, and the brain soon loses its ability to circulate blood in areas responsible for important thought processes. "Once chronic inflammation sets in, blood vessels constrict, blood flow is reduced and brain tissue is damaged," the researcher explained. "At the age of 65, the average person's brain shrinks about one percent a year, but in a patient with diabetes, brain volume can be lowered by as much as 15 percent."
Dr. Novak observed significant deterioration in regions vital to problem-solving, decision-making and memory in her patients with type 2 diabetes. They were also more likely to be depressed than people without diabetes, and they exhibited greater motor function decline, walked slower and had a higher risk of falls attributable to balance difficulties.
Dr. Novak's work may contribute to new strategies to prevent or treat functional and cognitive decline in people with diabetes. She advises doctors and their patients to take early steps to carefully control blood sugar and maintain blood vessel health, well before the signs of brain injury begin to surface.
(Novak V, Zhao P, Manor B, Sejdic E, Alsop D, Abduljalil A, Roberson PK, Munshi M, Novak P. Adhesion molecules, altered vasoreactivity, and brain atrophy in type 2 diabetes. Diabetes Care. 2011 Nov;34(11):2438-41. Epub 2011 Sep 16.)