More than a million cases of Alzheimer's disease in the United States have been attributed to a lack of exercise, and yet nearly one-third of Americans remain physically inactive [1]. Strong research evidence shows that exercise benefits the brain and can reduce your risk of falls, age-related diseases, and even death [2][3].
WHAT THE EVIDENCE SAYS There are many ways that exercise might benefit brain health. Clinical trials have found that exercise reduces chronic inflammation and increases the release of a protein that is very good for brain cells [4]. Exercise can improve cardiovascular and metabolic health, which are risk factors for Alzheimer's disease [5][6].
It's no surprise that observational studies found exercise is associated with a decreased risk of dementia. The reduction in risk is substantial—exercisers were up to 28% less likely to develop any type of dementia and 45% less likely to develop Alzheimer's disease, specifically [7][8].
Exercise may also help protect the brain as you age. Meta-analyses of observational studies suggest that physical activity—even at low-to-moderate levels—cuts your risk of cognitive decline by more than a third [8][9]. Clinical trials paint a slightly more mixed picture. Analyses of multiple clinical trials found that while resistance training and tai-chi improved cognition, aerobic exercise did not [10][11]. A couple of factors might explain these results. Some trials recruited people who were already fit, so additional exercise might have no added benefit. Also, most clinical trials last less than six months, while observational studies often track people over a number of years. The cognitive benefits of physical activity may take longer than six months to appear. If you carry the APOE4 gene allele, exercise may offer even more protection [12–16], though again short-term exercise didn’t show this benefit [4].
WHAT YOU CAN DO The World Health Organization recommends that adults get at least 150 minutes of moderate-intensity (or 75 minutes of vigorous-intensity) aerobic exercise every week, along with at least two days of muscle-strengthening activities [17]. No specific type of exercise has been shown to improve brain health more or less than another, so do what you enjoy. Options for aerobic exercise include brisk walking, jogging, tennis, or swimming and muscle-strengthening activities include weight training, rock climbing, and yoga [10].
Exercise does carry some risk of injury, particularly for sedentary people who suddenly start a vigorous exercise routine. These risks decrease if you exercise regularly [3]. If you need help choosing an appropriate workout for your fitness level, consult a doctor. Whatever you choose, avoid prolonged sitting, which may pose health risks even for those who exercise regularly [18].
Nick McKeehan is a member of the ADDF's Aging and Alzheimer's Prevention program. He evaluates the scientific evidence for and against therapies to promote brain health and/or prevent Alzheimer's disease at our website CognitiveVitality.org and contributes regularly to the site's blog. Mr. McKeehan previously served as Chief Intern at Mid Atlantic Bio Angels (MABA) and was a research technician at Albert Einstein College of Medicine investigating repair capabilities of the brain. Mr. McKeehan received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. He also writes about the biotechnology industry for 1st Pitch Life Science.
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