Physical exercise in the prevention and treatment of Alzheimer's disease

Abstract

Dementia is one of the greatest global challenges for health and social care in the 21st century. Alzheimer's disease (AD), the most common type of dementia, is by no means an inevitable consequence of growing old. Several lifestyle factors may increase, or reduce, an individual's risk of developing AD. Much has been written over the ages about the benefits of exercise and physical activity. Among the risk factors associated with AD is a low level of physical activity. The relationship between physical and mental health was established several years ago. In this review, we discuss the role of exercise (aerobic and resistance) training as a therapeutic strategy for the treatment and prevention of AD. Older adults who exercise are more likely to maintain cognition. We address the main protective mechanism on brain function modulated by physical exercise by examining both human and animal studies. We will pay especial attention to the potential role of exercise in the modulation of amyloid β turnover, inflammation, synthesis and release of neurotrophins, and improvements in cerebral blood flow. Promoting changes in lifestyle in presymptomatic and predementia disease stages may have the potential for delaying one-third of dementias worldwide. Multimodal interventions that include the adoption of an active lifestyle should be recommended for older populations.

Keywords: Aerobic exercise; Dementia; Exercise training; Lifestyle factors; Multidomain interventions; Resistance exercise.

Fig. 1

Brain function in normal aging and Alzheimer's disease is influenced by lifestyle factors. The usual trajectory for brain aging (orange line) indicates that, years before death, an individual shows signs of mild cognitive impairment. In some cases, that cognitive damage takes place many years before death and even leads to dementia (red line). By modifying lifestyle factors through multimodal interventions, an individual can delay the onset of cognitive impairment until a very advanced age (green line).

Fig. 2

Potential protective mechanisms of exercise on brain aging.

Fig. 3

CBF by age groups (at an interval of 5 years), measured by MRI (De Vis et al., used with permission of John Wiley and Sons). CBF = cerebral blood flow; MRI = magnetic resonance imaging.