Johns Hopkins Scientists Uncover Surprising Brain Health Benefits

Recent studies have shown that both intermittent fasting and a standard healthy diet improve brain function in obese adults with insulin resistance, with intermittent fasting resulting in better cognition.

Researchers from the Johns Hopkins University School of Medicine and the National Institute on Aging say: National Institutes of Health The study, which looked at 40 obese elderly people, reported: Insulin Participants were randomly assigned to follow either an intermittent fasting regimen or a standard healthy diet recommended by the United States Department of Agriculture (USDA). The study provides important insight into the potential brain health benefits of both diets.

Insulin resistance is a hallmark of type 2 diabetes and is common in obese people. Research suggests that people with insulin resistance are at higher risk for diabetes than normal. Alzheimer’s disease Various weight loss methods are widely used to reduce the risk of disease and other cognitive disorders.

Findings and Methods

Previous studies from Johns Hopkins University in animal models of diabetes and Alzheimer’s disease have shown that intermittent fasting can improve cognitive function and insulin sensitivity. Cell metabolismtested the effects of intermittent fasting in women and men at risk for cognitive impairment, providing a “blueprint” to use a broad panel of biomarkers to assess the diet’s impact, including analysis of extracellular vesicles — tiny globs of material released by neurons, a type of brain cell that transmits messages, the authors write. Such neuron-derived extracellular vesicles are released into circulating blood and were collected over an eight-week period from participants in the new study, who each followed one of two diets.

According to Dr. Mark Mattson, an adjunct professor of neuroscience at the Johns Hopkins University School of Medicine and former director of the neuroscience laboratory at the National Institute on Aging in Baltimore, the results showed that both types of eating plans had benefits in terms of reducing insulin resistance and improving cognition, and that improvements in memory and executive function were seen with both diets, but the effects were more pronounced with the intermittent fasting diet. “Other scientists may want to incorporate the[brain]markers[we used]into larger studies of diet and brain health,” Dr. Mattson says.

Survey Methodology and Participant Demographics

Because people with obesity and insulin resistance may be at higher risk for cognitive impairment and Alzheimer’s disease than those with normal metabolism and BMI, Dimitrios Kapogiannis, MD, PhD, chief of the Division of Human Neuroscience at the National Institute on Aging and adjunct associate professor of neurology at the Johns Hopkins University School of Medicine, developed a method to isolate neuron-derived extracellular vesicles from blood. His lab has found molecular evidence of insulin resistance in extracellular vesicles shed from neurons in patients with diabetes and Alzheimer’s disease, and because blood samples are relatively easy to obtain, they seemed like a good candidate for widespread use.

To test the effects of the two diets on biomarkers of brain function, participants in the new study were recruited between June 2015 and December 2022 and underwent four in-person assessments at a facility run by the National Institute on Aging at MedStar Harbor Hospital in Baltimore. Forty of the participants completed the eight-week study. Twenty were also assigned to an intermittent fasting diet that restricted calories to one-quarter of the daily recommended intake for two consecutive days a week, while the remaining five days followed the USDA Healthy Living diet (consisting of fruits, vegetables, whole grains, lean protein, low-fat dairy, limited added sugars, saturated fats, and sodium). The USDA Healthy Living diet was assigned to the other 20 study participants for each day of the week.

The average age of participants in both groups was 63 years old. There were 25 white, 14 black, and one Hispanic. There were 24 men and 16 women. All were obese and insulin resistant.

The researchers found that both diets had similarly positive effects on reducing insulin resistance markers in extracellular vesicles, improving BrainAGE (a measure of the brain’s biological age using structural MRI data), and reducing glucose concentrations in the brain, which is a corollary of increased glucose usage.

Both diets improved common measures of metabolic health, including weight, BMI, waist circumference, blood lipids like cholesterol, and insulin resistance. Executive function and memory (a set of mental skills that help you plan and achieve your goals) improved by about 20% in the intermittent fasting group compared to the healthy living diet group.

Observation and health precautions

Some study participants reported mild side effects, including constipation, loose stools, and occasional headaches.

The researchers also found elevated levels of neurofilament proteins (structural proteins in neurons) in both diet groups, but mainly in the intermittent fasting group. What this means in terms of brain health is unclear.

“This is an indicator that we will continue to evaluate in future studies,” Mattson said. “Neurons release many proteins, and the idea is that intermittent fasting may be causing some kind of neuroplasticity (changes in structure) in neurons, which causes the release of neurofilament proteins.”

Johns Hopkins University researchers caution that intermittent fasting can be harmful for some people, such as those with type 1 diabetes or eating disorders, so people interested in trying it should plan carefully with their health care provider.

Reference: “Brain Responses to Intermittent Fasting and Healthy Eating in Older Adults” Dimitrios Kapogiannis, Apostolos Manolopoulos, Roger Mullins, Konstantinos Avgerinos, Francesca Delgado Peraza, Maya Mustapic, Carlos Nogueras Ortiz, Pamela J. Yao, Krishna A. Putya, Janet Brooks, Qinghua Chen, Shalaila S. Haas, Ruiyan Ge, Lisa M. Hartnell, Mark R. Cookson, Josephine M. Egan, Sofia Frangou, Mark P. Mattson, June 19, 2024 Cell metabolism.
DOI: 10.1016/j.cmet.2024.05.017

This research was supported by the National Institute on Aging at the National Institutes of Health (ZIAAG000966, ZIAAG000975).