Preventive effects of regular physical exercise against cognitive decline and the risk of dementia with age advancement.

With age advancement, cognitive function is impaired and the risk of dementia is increased under the influence of normal or pathological cortical and subcortical neuronal alterations. Significant researches has been undertaken to analyze the preventive effects of exercise against the decline of cognitive function and the risk of dementia (e.g., Alzheimer's disease), particularly during the past 10 years. The aim of this short review is to report the scientific knowledge, relating to these effects, that has been obtained during the past 10 years. Acute physical exercise raises the cardiac output in response to increased needs for oxygen and energetic substrates compared to the state of rest, which increases the cerebral blood flow. The increased cerebral blood flow triggers various neurobiological mechanisms in the brain tissue. Repeated and regular physiological modifications related to exercise facilitate the synthesis of cerebral tissue. Regular physical exercise (rPE) may thus increase angiogenesis, neurogenesis, synaptogenesis, and the synthesis of neurotransmitters in different cerebral structures involved in cognition due to an increase in the liberation of neurotrophic factors and the production of enzymatic antioxidants. There is an inversely proportional relationship between the amount of physical activity undertaken and the risk of cognitive decline and/or the development of neurodegenerative disease. The synthesis of cerebral tissue under the influence of aerobic rPE may increase the volume of the gray and white matters of the prefrontal and temporal cortical areas as well as the volume of the hippocampus. Moreover, coordination exercise stimulates cognitive function, thereby inducing positive adaptations of cerebral function when regularly practiced. The possible effects of other types of exercise that weakly stimulate the cardiovascular system or cognitive function, such as stretching and strength training, are also beneficial but their mechanistic explanations require further exploration.