Physical activity has been suggested to attenuate the pathophysiology of dementia. Regular physical exercise is an important element in overall health promotion and studies conducted since early 90’s showed that it might be an effective strategy to delay the onset of dementia by improving blood flow to the brain. More recently, researchers found that reduced loss of hippocampal brain tissue in the aging brain is related to the level of physical fitness, in agreement with animal studies also showing increased brain cortical thickness with voluntary exercise and other positive brain changes ultimately leading to a healthier brain. The encouraging results of these studies prompted the performance of longitudinal and randomized trials, which overall confirm that physical exercise enhances cognitive function in adults. When 134 nursing home residents with AD where divided in two groups undergoing either usual care or collective exercise for 60 minutes twice a week, a slower disability decline and increased gait speed were shown after 12 months of intervention in the group undergoing collective exercise compared to the usual care group. In summary, studies produced so far in the field of physical activity and dementia prevention (either primary or secondary) in the elderly are not comparable and guidelines for the primary and secondary prevention of dementia cannot be drafted. This is due to the self-addressed nature of cognitive performance and performed physical activity as well as to the populations studied (mainly nursing home residents, compliance, to the time-window of applied physical intervention, and, in general, to the dyshomogeneity of the methods applied. Physical activity training ranges from 150 min five times per week to 20 min three times per week). Occupational therapies sometimes included in studies on physical activity and dementia prevention also confound results on the latter issue, as no or insufficient evidence is present for the efficacy of counseling the primary caregiver of dementia patients about maintaining the patient’s cognitive or functional abilities, respectively. The possibility that physical activity may substantially enhance the brain reserve of the individual is also a critical one which needs to be carefully explored. The current recommendations of regular physical activity as a key component of successful aging can be given to both healthy adults and to elderly subjects with and without cognitive impairment. While awaiting for the results of large ongoing randomized controlled trials in the coming decade, it is to recommend that persons with MCI try to pursue a moderate but regular, variable exercise program consisting of at least 30 minutes three times weekly of walking alternating with aerobically challenging exercise and group sports.
Participation in leisure activities, including physical activities, has been consistently associated with a reduced risk of dementia. A comprehensive review (meta-analysis) recently showed that subjects who performed physical activity at baseline had a significantly reduced risk of cognitive decline during follow-up. When studies were grouped according to the different levels of physical activity, subjects who reported to be more physically active had a 38% reduced risk of cognitive decline compared to those who reported being sedentary. The significant protection against cognitive decline during follow-up was still observed when low-to-moderate levels of physical activity were taken into consideration. Positive were also the results of an earlier meta-analysis of training interventions that examined whether an aerobic fitness intervention can have a robust and beneficial influence on cognition in sedentary older adults: fitness training increased performance 0.5 SD on average, regardless of the type of cognitive task, the training methods or participants characteristics. There is also some more recent evidence from randomized controlled trials. A 24-week home-based program of physical activity (approximately participants performed at least 150 min of moderate-intensity physical activity per week, mainly walking) improved cognitive function in older adults with subjective and objective mild cognitive impairment; the benefits were evident after 6 months and persisted for at least another 12 months following the discontinuation of the intervention.
Observational studies have shown that individuals who exercise regularly are at reduced risk for Alzheimer’s disease. Adults who exercised in midlife were found to be less likely to develop dementia after age 65, compared with their sedentary peers. In controlled trials, aerobic exercises such as brisk walking for 40 minutes 3 times per week reduces brain atrophy and improves memory and other cognitive functions