A new study adds to growing evidence that the complications of diabetes may extend to the brain, causing declines in memory, attention and other cognitive skills.
The new research showed that over the course of about a decade, elderly men and women with diabetes -- primarily Type 2, the form of the disease related to obesity and inactivity -- had greater drops in cognitive test scores than other people of a similar age. The more poorly managed their disease, the greater the deterioration in mental function. And the declines were seen not just in those with advanced diabetes. The researchers found that people who did not have diabetes at the start of the study but developed it later on also deteriorated to a greater extent than those without the disease.
"What we've shown is a clear association with diabetes and cognitive aging in terms of the slope and the rate of decline on these cognitive tests," said Dr. Kristine Yaffe, a professor of psychiatry and neurology at the University of California, San Francisco. "That's very powerful."
While correlation does not equal causation and the relationship between diabetes and brain health needs further study, the findings, if confirmed, could have significant implications for a large segment of the population. Nationwide, nearly a third of Americans over the age of 65, or roughly 11 million people, have diabetes. By 2034, about 15 million Medicare-eligible Americans are expected to have the disease.
Previous studies have shown that Type 2 diabetes correlates with a higher risk of Alzheimer's disease and dementia later in life. But how one leads to the other has not been well understood. While some scientists speculate that inflammation and vascular damage caused by chronically high blood sugar levels over many years is the culprit, findings from research have been inconsistent. And until now, little was known about the effect, if any, that newly diagnosed diabetes would have on cognitive function.