The Effectiveness of Dietary-Induced Ketogenesis on Cognition in Older Adults: A Scoping Review of the Literature

There is growing interest in the effect of dietary interventions in people living with memory impairment and delaying cognitive decline. Investigation of alterations in glucose metabolism and dietary-induced ketogenesis in older adults is a recent growing area of research. Ketone bodies are an important alternative energy source in the brain and may be beneficial to people developing or who already have memory impairment or those with Alzheimer’s disease. This scoping review aims to evaluate the available evidence on dietary-induced ketogenesis and its effect on cognition in older adults and the factors affecting feasibility of the dietary interventions to inform the design of future studies. The scoping review methodology explored the current knowledge about dietary interventions related to dietary-induced ketogenesis and cognition in older adults and identify gaps in the literature. Eleven dietary intervention studies included in the review demonstrated that both medium-chain triglyceride supplementation and ketogenic diets induce ketosis. Nine of these studies demonstrated that dietary-induced ketogenesis could lead to an improvement in cognitive functions, but the evidence remains inconclusive. Most of the included studies showed evidence to suggest that dietary-induced ketogenesis improves cognitive functions in older adults. However, the number of published papers is small and there were differences in the design and types of the dietary interventions (medium-chain triglyceride supplementation, ketogenic diet) along with high drop-out rates in some studies which limits the generalization of the findings. Although methodologies used in the studies vary, the findings warrant the need for further research with larger sample sizes in people at different stages of cognitive impairment, and to develop strategies to improve adherence to the intervention.