Comparing the effects of low protein, high carbohydrate diets and caloric restriction on brain aging in mice.

Calorie restriction (CR) increases lifespan and improves brain health in mice. Ad libitum low protein, high carbohydrate (LPHC) diets also extend lifespan, but it is not known whether they are beneficial for brain health. We compared hippocampus biology and memory in mice subjected to 20% CR or provided ad libitum access to one of three LPHC diets, or to a control diet. At age 15 months, patterns of RNA expression in the hippocampus were similar between CR and LPHC diets for genes associated with longevity, cytokines and dendrite morphogenesis. Nutrient sensing proteins including SIRT1, mTOR and PGC1α were also influenced by diet, however the effects varied by sex. CR and LPHC diets were associated with increased dendritic spines in dentate gyrus neurons. CR and LPHC diets led to modest improvements in the Barnes Maze and Novel Object Recognition. LPHC diets recapitulate some of the benefits of CR on brain aging. 30 samples, 6 biological replicates in each group.