Resilience to Alzheimer's disease: the role of physical activity

BACKGROUND: Although Alzheimer's disease (AD) is a neurodegenerative pathology characterized by accumulation of β-amyloid plaques and neurofibrillary tangles at cerebral level, recent studies highlighted that AD might be the result of many altered physiological processes occurring at whole-organism level. The ability to adapt to stressors by "bending" but not "breaking" can be considered as "resilience". Individuals incline to withstand such pathophysiological challenges, can be considered more resilient than those that do not. Noticeably, recent literature provide evidence of several exercise-induced positive effects in AD patients including improved brain plasticity, increased adrenal sensitivity, increased vascular health, ameliorations of nitric oxide bioavailability and mitochondrial function. This review explores what resilience means in the AD milieu and the physiological mechanisms by which physical activity may mediate adaptive positive processes that enhance resilience. METHODS: A comprehensive PubMed search was conducted to identify studies about the role of exercise in AD resiliency. The following terminology was applied: Alzheimer resilience, brain resilience, metabolic resilience, cardiovascular resilience, mitochondrial resilience and exercise resilience. RESULTS: Seventy-three studies were included. Five papers defined Alzheimer's resilience, 15 papers brain resilience, five cardiovascular resilience, one metabolic resilience, 11 mitochondrial resilience, and 7 exercise resilience. Other twenty-six paper were identified from reference list of authors' knowledge. CONCLUSION: knowing that disturbances in brain, neuroendocrine, vascular and mitochondria metabolism are important events in neurodegeneration and dementia development, the ability of exercise to trigger adaptive mechanisms might represent an important non-pharmacological strategy to improve resilience to AD.