Alzheimer’s disease may be related to metabolic dysfunction and at least partly influenced by modifiable lifestyle factors, according to a new study. 

Much Alzheimer’s research has focused on beta-amyloid plaque buildup in the brain, but some researchers now believe that these plaques are simply a symptom and not a cause of the disease.

“Alzheimer’s Disease is increasingly being referred to as insulin resistance of the brain or Type 3 Diabetes,” said senior study author Benjamin Bikman, Ph.D., of Brigham Young University. “Our research shows there is likely a lifestyle origin to the disease, at least to some degree.”

Metabolic dysfunction disrupts the body’s ability to turn food into energy and get rid of waste products effectively. It is known to contribute to the development of numerous diseases such as type 2 diabetes.

Bikman and colleagues conducted a post-mortem study of the brains of former Alzheimer’s disease patients. They found widespread evidence of impaired glucose metabolism, suggesting a fundamental genetic deficit in the brain’s ability to use glucose, reported lead author Erin Saito, a Ph.D. student, also of Brigham Young University.

The brain gets some of its fuel from glucose or ketones, so when it can’t use glucose, it needs ketones, Saito and colleagues wrote. But the typical high-carbohydrate American diet interferes with the brain’s access to this fuel, they wrote.

“The inability to use glucose increases the value of ketones. However, because the average person is eating insulin-spiking foods so frequently, there’s never any ketones available to the brain,” Bikman said. “I look at these findings as a problem we’ve created and that we’re making worse.”

Treatments involving ketones may be able to support brain metabolism and slow cognitive decline associated with Alzheimer’s disease, Bikman and colleagues concluded.

Other studies have found similar links between Alzheimer’s disease and lifestyle. A 2020 investigation, for example, found that five key factors lowered Alzheimer’s risk: physical activity, not smoking, light-to-moderate alcohol consumption, a high-quality diet, and cognitive activities. 

The current study was published in the journal Alzheimer’s & Dementia.