SOURCE: Rachel Huxley, D.Phil., M.A., head, School of Public Health, Curtin University, Perth, Australia; James M. Ellison, M.D., M.P.H., Swank Foundation endowed chair, memory care and geriatrics, Christiana Care Health System, Wilmington, Del.; Dec. 17, 2015, online, Diabetes Care
THURSDAY, Dec. 17, 2015 (HealthDay News) -- Women with type 2 diabetes may be at risk of developing a type of dementia resulting from damaged or blocked blood vessels to the brain, a new research review suggests.
Analyzing data from nearly 2.5 million participants in 14 studies, an international team of scientists found that women with type 2 diabetes may have a nearly 20 percent higher risk of developing vascular dementia than men with diabetes. Vascular dementia is characterized by memory, thinking and language difficulties due to reduced blood flow to the brain, according to the Alzheimer's Association.
But the risk for any form of dementia was the same for both sexes -- about 60 percent higher for diabetics than for people without the disease, according to the research, published online Dec. 17 in the journal Diabetes Care.
"It's plausible that the same mechanisms that drive the greater excess risk of heart disease and stroke in women with diabetes ... are also causing the excess risk of vascular dementia," said study author Rachel Huxley, head of the School of Public Health at Curtin University in Perth, Australia.
"We still don't fully understand why women with diabetes are at excess risk of vascular disease and it may be related to sex hormones," Huxley added. "It may also be that blood glucose levels in women with diabetes are much more ... difficult to control than in men with diabetes."
But, the study didn't prove that type 2 diabetes caused either type of dementia; it merely showed an association between the two conditions.
About 44 million people worldwide are affected by dementia. According to study documents, dementia symptoms stem from two main causes: Alzheimer's disease, which isn't caused by blood vessel damage, or vascular dementia, which is preventable. Lifestyle risk factors for vascular dementia include type 2 diabetes, smoking and obesity.
The new review built on research spanning more than a decade, Huxley said, looking at records from 2.3 million individuals without dementia and more than 102,000 dementia patients.
While the nearly 20 percent greater risk of vascular dementia was noted among women compared to men with diabetes, the risk for nonvascular dementia (predominantly Alzheimer's disease) associated with having diabetes was roughly the same in both genders -- but still 40 percent higher than for people without diabetes.
Huxley said it's still not clear to scientists why type 2 diabetes may increase the chances of dementia, regardless of gender.
"It's a good question but one to which we don't have a definitive answer," she said. "Some studies suggest that vessel damage in the brain caused by diabetes is an important factor."
Dr. James Ellison, the Swank Foundation endowed chair in memory care and geriatrics at Christiana Care Health System in Wilmington, Del., said it's well-known that diabetes damages blood vessels, and that aging of the blood vessels is a major contributor to the development of vascular dementia.
"But why it should be a more serious risk for women than men isn't readily apparent," said Ellison, who wasn't involved in the new study. "The message to clinicians is to consider screening aggressively for diabetes and prediabetes and to be very attentive to women who are in higher risk groups, like women with gestational diabetes." Gestational diabetes is pregnancy-related.
Huxley said people with diabetes shouldn't panic about dementia, noting that many healthy lifestyle measures can offset risks.
"Individuals at risk of developing diabetes and those with overt diabetes can do many things to reduce their risk of dementia, such as quitting smoking, increasing the level of physical activity, eating a healthy diet, minimizing alcohol intake and even losing a few pounds," she said.
"The take-home message is that for many people -- with and without diabetes -- dementia is not inevitable," Huxley added. "Maintaining a healthy weight, watching what you eat and keeping your brain fit and active are some of the things that may reduce future risk of dementia. There's some truth in the adage, 'A healthy body equals a healthy mind.'"
The Alzheimer's Association offers more about vascular dementia.