Normal aging of memory with and without physical exercise

Normal aging in general population is associated with memory declines. The prefrontal cortex dependent working memory and the hippocampal formation dependent episodic memory are the most affected memories in older population. Individuals with the compromised memories undergo a series of age-associated changes measured by behavioral performance tasks, including slowed behavioral reaction time and reduced accuracy rate. These age-associated changes of memory functions are coupled with altered neural structures within selective regions of the prefrontal cortex and the hippocampal formation in older adults. Electrophysiological studies and functional neuroimaging studies confirmed and extended the behavioral data by providing in vivo measurements of brain functions. The changes in behavioral performance correlate with altered brain activations in selective cortical circuits and reduced secretion of brain derived neurotrophic factors (BDNF). Appropriate brain activations and BDNF secretion are critical for intact memory functions. Although age-associated functional compromise in memory is inevitable, it can be slowed or reversed by appropriate physical exercise. Animal model and human subjects' studies demonstrate the effects of physical exercise on brain morphology, regional activations, and the level of BDNF. In older adults, exercise engagement is associated with superior behavioral performance in memory tests, less brain volumetric atrophy, brain activation associated with enhanced memory performance, and increase BDNF in the prefrontal cortex and the hippocampal formation. Therefore, physical exercise can be used at a non-pharmaceutical approach to slow or reverse age-associated memory function decline.