A new study led by the National Institute on Aging (NIA) demonstrates that older adults with obesity and metabolic problems can improve their brain health by adopting a healthy diet. The research, published in Cell Metabolism, compared the effects of intermittent fasting and the U.S. Department of Agriculture (USDA) healthy living diet on brain changes in older adults over an eight-week period.
The study addresses the growing concern that insulin resistance, a metabolic condition impairing glucose removal from the bloodstream, is linked to an increased risk of dementia and Alzheimer's disease. Researchers aimed to determine if dietary modifications could enhance overall health and cognitive function in this vulnerable population.
Trial Design and Methods
The clinical trial involved 40 older adults, with an average age of 63, all exhibiting insulin resistance. Participants were randomly assigned to either a 5:2 intermittent fasting diet or the USDA healthy living diet. The intermittent fasting diet restricted calorie intake to a quarter of the recommended daily amount for two consecutive days each week. The healthy living diet emphasized fruits, vegetables, whole grains, lean proteins, and low-fat dairy, while limiting added sugars, saturated fats, and salt.
Researchers collected plasma samples via blood draws at the beginning, fourth week, and eighth week of the study to isolate neuron-derived extracellular vesicles (NDEVs). NDEVs, small vesicles released by neurons into the bloodstream, were used as a non-invasive tool to assess neuronal insulin usage. Cognitive performance was evaluated, and magnetic resonance imaging (MRI) and magnetic resonance spectroscopy were employed to measure the rate of brain aging and glucose utilization. Additionally, NDEVs and cerebrospinal fluid were analyzed for Alzheimer’s biomarkers.
Key Findings
Both dietary interventions—intermittent fasting and the healthy living diet—resulted in a reduced pace of brain aging and improved cognitive function and insulin resistance. Notably, intermittent fasting led to more pronounced improvements in executive functions and greater weight loss. However, neither diet significantly altered Alzheimer’s biomarkers.
Implications and Future Directions
While the dietary changes did not appear to directly affect dementia risk, the study underscores the potential of diet to enhance brain health in older individuals with metabolic impairments. According to the researchers, this work establishes a foundation for larger clinical trials focused on dietary interventions.
"This research contributes a framework for larger clinical trials on dietary interventions," the authors noted in the study.
The research was supported in part by NIA grants ZIAAG000966 and ZIAAG000975.
