A recent study conducted by Florida Atlantic University and CINVESTAV, Mexico City, Mexico, has revealed how exercise can help maintain memory function during aging. The study focused on the effects of long-term running on a network of new hippocampal neurons that were generated in young adult mice at middle age. The researchers found that running throughout middle age kept old adult-born neurons wired, potentially preventing or delaying aging-related memory loss and neurodegeneration.
As individuals age, there is often a decrease in cognitive functions. The hippocampus and neighboring cortices, which are crucial for learning and memory, are among the initial parts of the brain to be affected. Cognitive performance deficits have been linked to a diminished hippocampal volume and deteriorated synaptic connectivity between the hippocampus and the (peri)-entorhinal cortex.
However, increasing evidence suggests that physical activity can help delay or avert these structural and functional diminutions in older individuals. The new study offers new insight into the benefits of exercise and highlights the importance for adults, particularly those in middle age, to maintain physical activity throughout their lives.
The researchers used a unique rabies virus-based circuit tracing approach to analyze the neural circuitry of adult-born neurons in middle-aged mice. They found that long-term running significantly increased the number of adult-born neurons and enhanced the recruitment of presynaptic (sub)-cortical cells to their network. This wiring of old adult-born neurons plays a role in the maintenance of episodic memory encoding during aging.
“Long-term exercise profoundly benefits the aging brain and may prevent aging-related memory function decline by increasing the survival and modifying the network of the adult-born neurons born during early adulthood, and thereby facilitating their participation in cognitive processes,” said Henriette van Praag, Ph.D., corresponding author and associate professor of biomedical science at FAU’s Schmidt College of Medicine.
The study also revealed that running not only rescued perirhinal connectivity but also increased and altered the contribution of the entorhinal cortices to the network of old adult-born neurons. These findings suggest that running can enhance pattern separation ability, our ability to distinguish between highly similar events and stimuli, which is closely linked to adult neurogenesis.
“Aging-related memory function decline is associated with the degradation of synaptic inputs from the perirhinal and entorhinal cortex onto the hippocampus, brain areas that are essential for pattern separation, and contextual and spatial memory,” explained van Praag. “Running also substantially increases the back-projection from the dorsal subiculum onto old adult-born granule cells, providing navigation-associated information and mediating the long-term running-induced improvement in spatial memory function.”
The study provides further evidence of the positive effects of exercise on memory function during aging. By promoting the survival and modifying the network of adult-born neurons, exercise can potentially prevent or delay age-related memory decline. These findings emphasize the relevance of including exercise in our daily lives, starting from young adulthood and continuing throughout middle age.
The research was supported by the FAU Stiles-Nicholson Brain Institute, the Jupiter Life Sciences Initiative, and the Cinvestav Scientific Research and Technological Development Fund. Further studies are needed to fully understand the mechanisms through which exercise impacts memory function and to explore potential interventions for age-related cognitive decline.
The study, titled “Running throughout Middle-Age Keeps Old Adult-Born Neurons Wired,” was published in the journal eNeuro. Study co-authors include researchers from UC Davis, FAU’s Schmidt College of Medicine and Stiles-Nicholson Brain Institute, and the University of Pennsylvania.