Prediabetes and type 2 diabetes are marked by insulin resistance — and preventing or reversing insulin resistance may prevent dementia, including Alzheimer’s.
Alzheimer's disease, the most common form of memory robbing dementia, affects about five million Americans, according to the Alzheimer’s Association. Although it’s associated with growing older, Alzheimer’s disease is not a normal part of aging.
Several risk factors, ranging from genetics and concussions, have been identified, but pin-pointing a cause for Alzheimer’s — and finding a cure — has remained elusive. There’s mounting evidence, however, that insulin resistance, which leads to higher than normal blood sugar levels, plays an important role in many cases.
That’s good news. It means preventing or reversing insulin resistance may help prevent Alzheimer’s disease.
It would also explain why lifestyle strategies — including regular exercise, keeping weight under control, and eating a nutritious diet along the lines of the Mediterranean style of eating — lower your risk for dementia, according to the National Institute on Aging. These same strategies lower your risk for insulin resistance and type 2 diabetes.
What is insulin resistance?
When insulin resistance develops, cells throughout your body can’t respond normally to insulin, the blood sugar regulating hormone your pancreas produces. Cells are unable to easily absorb glucose from your bloodstream, and excess blood sugar (also called blood glucose) accumulates. If blood glucose is higher than normal but not yet in the type 2 diabetes range, you have prediabetes; if it is higher, you have type 2 diabetes.
Type 2 Diabetes and Alzheimer’s disease are known to be connected. People with diabetes have an increased risk for Alzheimer’s, and the Alzheimer’s Association points out there are several possibilities for this link. Diabetes raises your risk of heart disease and stroke, which can damage blood vessels in your brain, contributing to dementia.
High blood sugar or insulin resistance may also contribute to unbalanced chemicals your brain needs to function normally. In addition, elevated blood sugar is linked to inflammation, which may play a role in Alzheimer’s disease.
What is type 3 diabetes?
Brown University neuropathologist Suzanne de la Monte, MD, who has long studied the connection between insulin resistance, diabetes, and dementia in both animal experiments and the brains of people who died from Alzheimer’s, calls Alzheimer’s disease type 3 diabetes — diabetes of the brain.
Brown and colleagues have found insulin resistance not only hampers the ability to think clearly but also appears to play a role in forming the tangled beta amyloid plaques found in the brains of Alzheimer’s patients.
To investigate whether people with insulin resistance are more likely to develop dementia, Tel Aviv University (TAU) scientists studied almost 500 research subjects for over 20 years. At the beginning of the study, the participants were checked for insulin resistance with blood tests that measured their fasting blood glucose and insulin levels. A battery of tests was also used to assess the patients’ thinking skills, including their memory and attention spans.
The research participants were retested in 15 years, and again five years later. The results showed those who had insulin resistance — whether or not they had high enough blood sugar to be diagnosed with diabetes — experienced an accelerated decline in their executive function (mental abilities such as paying attention, planning and organizing) and memory. The researchers adjusted their findings for any heart disease risk factors and other known dementia risks found in the research subjects — but the conclusions remained the same. Over time, insulin resistance was strongly associated with signs of dementia.
"These are exciting findings because they may help to identify a group of individuals at increased risk of cognitive decline and dementia in older age," said researcher David Tanne, PhD, professor of neurology in TAU's Sackler School of Medicine.
"We know that insulin resistance can be prevented and treated by lifestyle changes and certain insulin-sensitizing drugs. Exercising, maintaining a balanced and healthy diet, and watching your weight will help you prevent insulin resistance and, as a result, protect your brain as you get older."
March 06, 2023
Janet O’Dell, RN