A study by ISU researchers has shown that insulin resistance can lead to an increased risk of Alzheimer’s disease.

The team led by Postdoc Research Associate Auriel Willette measured insulin-resistant patients’ brain blood sugar usage. The food science team found that areas of the brain susceptible to Alzheimer’s used less energy.

“Insulin resistance is the inability of insulin to do its job,” Willette said.

Insulin’s purpose, Willette said, is to get energy in the form of blood sugar into bodily tissues such as muscles or the brain.

People who are resistant to the chemical require more insulin than others to supply organs with energy.

Resistance can be caused by a number of factors, including genetics and obesity, and can lead to health problems like diabetes and high blood pressure.

Resistance to the chemical has long been known to cause problems such as diabetes and high blood pressure, but the link to Alzheimer’s is new.

Willette, who has previously worked at the National Institute on Aging, came to Ames as a research scientist.

“I was interested in the nutrition program here, and they were interested in somebody who was a ‘brain guy,’ and I think I fit that particular niche pretty well,” Willette said.

The study measured its results by injecting a chemical called FDG, which a human body uses like blood sugar, but can be detected by a PET scanner.

FDG was injected into Alzheimer’s-prone research participants’ bloodstreams. They then performed memory tests in a PET scanner, during which their brain usage of blood sugar was measured.

“We used a fairly common memory test where we ask participants to listen to a list of 15 words. … People along the Alzheimer’s spectrum have intense problems with that,” Willette said.

Areas of the brain affected by Alzheimer’s used less blood sugar in resistant patients than non-resistant patients.

“If you have a lot of insulin resistance, then your memory will be worse off,” Willette said.

For many people, Willette said, insulin resistance and related memory loss can be prevented by moderate exercise, like housework, yardwork or brisk walking.

“Moderate exercise helps condition our muscles, and muscles are giant sinks for blood sugar,” he said.

Weight loss helps as well, but simply keeping one’s muscles toned contributes greatly to the fight against insulin resistance.

In the future, Willette will explore the insulin resistance-Alzheimer’s connection in obese individuals and will measure brain responses to other cognitive tasks in insulin resistance people.