Adaptive Capacity: An Evolutionary Neuroscience Model Linking Exercise, Cognition, and Brain Health

The field of cognitive neuroscience was transformed by the discovery that exercise induces neurogenesis in the adult brain, with the potential to improve brain health and stave off the effects of neurodegenerative disease. However, the basic mechanisms underlying exercise–brain connections are not well understood. We use an evolutionary neuroscience approach to develop the adaptive capacity model (ACM), detailing how and why physical activity improves brain function based on an energy-minimizing strategy. Building on studies showing a combined benefit of exercise and cognitive challenge to enhance neuroplasticity, our ACM addresses two fundamental questions: (i) what are the proximate and ultimate mechanisms underlying age-related brain atrophy, and (ii) how do lifestyle changes influence the trajectory of healthy and pathological aging? Recent work has shown that exercise can significantly improve brain structure and function in adults, especially during aging. We currently lack a comprehensive theoretical model to explain why exercise can lead to improved brain function. Taking an evolutionary neuroscience approach suggests that physiological systems, including the brain, respond to activity-related stress by expanding capacity, and that reductions in capacity represent an energy-minimizing strategy in response to inactivity. From an evolutionary neuroscience perspective, physical activity stresses brain function because of the cognitively demanding foraging context in which our ancestors engaged in aerobic physical activity. The ACM links evolutionary theory with cognitive neuroscience to show that cognitively demanding exercise is beneficial to brain structure and function, and that we can take advantage of this adaptation to help prevent declines due to aging and to developing neurological disease.