Active Life for Brain Health: A Narrative Review of the Mechanism Underlying the Protective Effects of Physical Activity on the Brain

Abstract

A growing body of evidence clearly indicates the beneficial effects of physical activity (PA) on cognition. The importance of PA is now being reevaluated due to the increase in sedentary behavior in older adults during the COVID-19 pandemic. Although many studies in humans have revealed that PA helps to preserve brain health, the underlying mechanisms have not yet been fully elucidated. In this review, which mainly focuses on studies in humans, we comprehensively summarize the mechanisms underlying the beneficial effects of PA or exercise on brain health, particularly cognition. The most intensively studied mechanisms of the beneficial effects of PA involve an increase in brain-derived neurotrophic factor (BDNF) and preservation of brain volume, especially that of the hippocampus. Nonetheless, the mutual associations between these two factors remain unclear. For example, although BDNF presumably affects brain volume by inhibiting neuronal death and/or increasing neurogenesis, human data on this issue are scarce. It also remains to be determined whether PA modulates amyloid and tau metabolism. However, recent advances in blood-based biomarkers are expected to help elucidate the beneficial effects of PA on the brain. Clinical data suggest that PA functionally modulates cognition independently of neurodegeneration, and the mechanisms involved include modulation of functional connectivity, neuronal compensation, neuronal resource allocation, and neuronal efficiency. However, these mechanisms are as yet not fully understood. A clear understanding of the mechanisms involved could help motivate inactive persons to change their behavior. More accumulation of evidence in this field is awaited.

Effects of Chronic Physical Exercise or Multicomponent Exercise Programs on the Mental Health and Cognition of Older Adults Living in a Nursing Home: A Systematic Review of Studies From the Past 10 Years

“…The beneficial effects of these interventions on the mental health and cognitive functions of older adults living in nursing homes could be explained by the fact that they improve cognitive vitality (Groot et al, 2016). This can be further explained by several physiological mechanisms (Umegaki et al, 2021). Physical exercise or multicomponent exercise programs can lead to the release of neurotrophic factors, such as a brainderived neurotrophic factor (Rehfeld et al, 2018;Ruiz-González et al, 2021) and insulin growth factor 1 (Kang et al, 2020;Stein et al, 2021), which can cross the blood-brain barrier to induce the synaptic plasticity and neurogenesis that to improve cognition.…”

Health Behaviors of Austrian Secondary School Teachers and Principals at a Glance: First Results of the From Science 2 School Study Focusing on Sports Linked to Mixed, Vegetarian, and Vegan Diets

“…It is well-accepted that healthy activity patterns and increased levels of PA, sports, and exercise result in higher cardiorespiratory fitness, and consequently, an improved level of health [ 4 ]. Regular exercise may be responsible for several benefits in all dimensions of health, including an increase in cognition even in the presence of neurodegeneration [ 5 ], prevention of stress and depression [ 6 , 7 ], maintenance of a good health profile even in adverse situations [ 8 ], and lower risk of developing discomforts in individuals who sit for prolonged amounts of time [ 9 ]. PA can be carried out in different ways and is categorized mostly as leisure recreational exercise (independent of commercial suppliers such as sports units, clubs, federations) or by participating in sports activities at a professional or amateur level (usually through membership in sports clubs).…”

Light intensity physical activity is beneficially associated with brain volume in older adults with high cardiovascular risk

“…We conducted a large scale cohort study with objectively measured physical activity and multiple brain volume indices, and our study's finding that LPA as well as MVPA is associated with brain volume seems valuable. Although the underlying mechanisms remain to be elucidated, physical activity is regarded to have a protective effect on the brain through several pathways ( 37 ). One of the major mechanisms is the increase of brain-derived neurotrophic factor (BDNF) in the blood.…”

“…BDNF is considered to support brain preservation by mediating neuronal survival and neurogenesis, and it may also preserve white matter structure ( 38 ). However, although there have been numerous studies on this topic, it is not fully understood how blood BDNF induced by physical activity actually preserves brain structure ( 37 ). Physical activity is also supposed to protect brain volume through anti-neurodegenerative mechanisms.…”