There is mixed evidence for exercise to improve neurogenesis and cognitive function in very old mice. Researchers here suggest that this is because the duration of an exercise program matters greatly, and there is a comparatively narrow window of time in which the result is a net gain in function. This may be an example of the frailty of old age: mild stresses such as exercise that are robustly beneficial in younger individuals become more of a balancing act between cost and benefit in age-damaged individuals. The results are interesting, and will likely guide further explorations of the effects of exercise in very old human patients. That said, it isn’t clear that the findings are in any way informative as to the dose-response curve for the effects of exercise on neurogenesis and cognitive function in old humans.
Hippocampal function is critical for spatial and contextual learning, and its decline with age contributes to cognitive impairment. Exercise can improve hippocampal function, however, the amount of exercise and mechanisms mediating improvement remain largely unknown. Here, we show exercise reverses learning deficits in aged (24 months) female mice but only when it occurs for a specific duration, 5 weeks,
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