Regular exercise slows aging more reliably and to a greater degree than any presently available medical technology, something that is more a statement on the poor nature of medicine at present than on the wondrous powers of exercise. The size of the effect is still small in the grand scheme of things; you can't reliably exercise your way to living to 100, and at present the majority of fit older people don't even make it to 90. You will, however, be better off than people who live a sedentary lifestyle. That exercise is better than available medicines at influencing the pace of aging will cease to be true in the near future as the first rejuvenation therapies emerge, but even then there is no reason to use that as excuse to slack on the basics of health maintenance. Exercise is both free and produces benefits, so take advantage.
Some lifestyle factors, such as physical activity (PA), could lower the risk of certain forms of dementia. In this article, our goal is to explore the role of PA in reducing the risks of age-related Alzheimer's disease (AD), vascular dementia (VaD), and mild cognitive impairment (MCI). PA throughout one's life can enhance cognitive function later in life, so it should be encouraged at every age. In contrast, sedentary behaviors, such as viewing television for extended periods over the course of years, can negatively affect cognitive function later in life. Moreover, those who were physically active in midlife have a reduced risk of developing depression in late life. Depression in late life has also been linked to dementia. Ideally, all adults should remain physically active throughout life, starting at a young age, to achieve optimal cognitive health as an older adult.
PA is effective in reducing risk for developing MCI in older adults, but the optimizing of exercise training (i.e., types of PA, intensity, duration), cardiorespiratory fitness, age, level of cognition, medications, and social environments, may all play roles in the outcome. For older adults who have already developed a form of cognitive impairment, whether mild, such as those with MCI, or moderate to severe, as with dementia, PA can improve cognitive function, when compared to those with cognitive impairment who are not physically active. Studies show that six to 12 months of exercise for those with MCI or dementia results in better cognitive scores than sedentary controls.
While the protective effect of PA on the aging brain is supported by numerous studies, the exact mechanisms are less clear. PA can increase blood flow to the brain, both during and shortly after a PA event, in response to increased needs for oxygen and energetic substrate. The increased brain/cerebral blood flow triggers various neurobiological reactions, which provide an increased supply of nutrients. Moreover, cerebral angiogenesis - the development of new blood vessels in the brain - is increased by PA, and the brain's vascular system is plastic, even in old age. The increased vascularization of the brain, as well as the regular increases in blood flow that periods of PA provide, may reduce the risks of MCI and AD, by nourishing more brain cells and helping to remove metabolic waste or AD-inducing amyloid-β.
Hypertension is one of the main risk factors for MCI, AD, and VaD. Hypertension can increase the risk of strokes, as well as small strokes that are often the cause of VaD. Since strokes can complicate AD and aggravate dementia symptoms, it follows that hypertensive individuals could benefit by lowering their blood pressure, regardless of their level of cognitive impairment. Even low-intensity PA for 30 min, three to six times a week for nine months, can significantly lower blood pressure in elderly adults. Because hypertension is a prominent risk factor, lowering blood pressure may be one of the mechanisms by which PA reduces the risk of many age-related neurodegenerative diseases.
Link: http://www.mdpi.com/...3425/7/2/22/htm
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