Examining brain responses to intermittent fasting and healthy diet in older adults

2024

Challenge

Cognitive decline with aging and the development of Alzheimer’s disease or a related form of dementia are more likely to occur in people who are overweight and have insulin resistance, a metabolic condition characterized by the inability of the body’s cells to remove sugar from the bloodstream. Insulin resistance is known to affect brain cells as well. Various healthy diets have been able to decrease body weight and insulin resistance and improve the way the body processes nutrients, but it has been unclear whether these diets can improve cognition and brain health.

Advance

IRP researchers conducted a clinical trial involving 40 insulin-resistant men and women who were, on average age, 63 years old. Participants were randomly chosen to follow one of two diets for 8 weeks: either a 5:2 intermittent fasting diet, which involves restricting calories to a quarter of the recommended daily intake for two consecutive days per week, or the US Department of Agriculture (USDA) healthy living diet. Both diets improved cognition and reduced signs of brain aging as shown via magnetic resonance imaging (MRI) scans. Notably, intermittent fasting had stronger effects on decreasing weight, reducing insulin resistance in the brain and body, and improving executive function, which is the ability to plan, strategize and solve problems. However, neither diet appeared to alter biological signs of Alzheimer’s disease.

Impact

The fact that intermittent fasting and following a healthy diet improve cognitive ability and decrease the pace of brain aging, in addition to their beneficial effects on general health, should further motivate people to maintain a healthy body weight and consume healthy food. The study’s findings also point to a need for larger and longer-lasting clinical trials of intermittent fasting to gauge its effects on brain aging and cognitive decline. Finally, because the researchers also produced preliminary evidence that the effects of both diets were influenced by sex and genetic factors like the APOE gene, the study suggests that future research on diets should consider the roles of those factors.

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