Calorie Restriction Slows Loss of Memory Function in Old Rats

Calorie restriction, the practice of consuming fewer calories while still maintaining an optimal intake of micronutrients, improves near all aspects of health and slows the progression of aging. This outcome appears to largely result from improved autophagy, or at least it is the case that functional autophagy is required for these benefits to occur in animal models. The relative extension of life span resulting from calorie restriction is much greater in short-lived species, as much as 40% in mice, but most likely only a few additional years in humans. The short-term health benefits are quite similar between mice and humans, however. It is certainly worth investigating as a lifestyle choice.

Age-related neurobiological changes significantly affect hippocampal structure and function, such that the main cognitive impairments associated with aging are related to the integrity of this brain structure, including the deterioration in spatial object recognition (SOR) memory. Previous studies have shown that intrinsic factors such as neuroinflammation, as well as lifestyle factors such as diet, can affect aging-associated brain functions and cognitive performance. In this regard, caloric restriction (CR) produces beneficial effects on health and life expectancy, although its ability to slow down age-dependent effects on cognitive decline and hippocampus (HPC) functioning remains unclear.

Therefore, we set out to evaluate the effects of CR on SOR memory in aged male Wistar rats, as well as those on hippocampal neuron loss, neurogenesis, and inflammation. The data show that CR in aged rats attenuates the decline in SOR memory, age-associated hippocampal neuron loss, and age-dependent microglial activation. Furthermore, we found a significant reduction in neurogenesis in the dentate gyrus of the old animals relative to adult rats. These findings support the positive effect of CR on SOR memory, suggesting that it dampens hippocampal neuronal loss and reduces proinflammatory activity.