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Fit Body, Fit Mind

Fit Body, Fit Mind

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].

  1. Norton S, Matthews FE, Barnes DE et al. (2014) Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. Lancet neurology 13, 788-794.
  2. Chan WC, Yeung JW, Wong CS et al. (2015) Efficacy of physical exercise in preventing falls in older adults with cognitive impairment: a systematic review and meta-analysis. J Am Med Dir Assoc 16, 149-154.
  3. Goodman JM, Burr JF, Banks L et al. (2016) The Acute Risks of Exercise in Apparently Healthy Adults and Relevance for Prevention of Cardiovascular Events. Can J Cardiol 32, 523-532.
  4. Jensen CS, Hasselbalch SG, Waldemar G et al. (2015) Biochemical Markers of Physical Exercise on Mild Cognitive Impairment and Dementia: Systematic Review and Perspectives. Front Neurol 6, 187.
  5. Way KL, Hackett DA, Baker MK et al. (2016) The Effect of Regular Exercise on Insulin Sensitivity in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis. Diabetes Metab J 40, 253-271.
  6. DeRight J, Jorgensen RS, Cabral MJ (2015) Composite cardiovascular risk scores and neuropsychological functioning: a meta-analytic review. Ann Behav Med 49, 344-357.
  7. Hamer M, Chida Y (2009) Physical activity and risk of neurodegenerative disease: a systematic review of prospective evidence. Psychological medicine 39, 3-11.
  8. Blondell SJ, Hammersley-Mather R, Veerman JL (2014) Does physical activity prevent cognitive decline and dementia?: A systematic review and meta-analysis of longitudinal studies. BMC Public Health 14, 510.
  9. Sofi F, Valecchi D, Bacci D et al. (2011) Physical activity and risk of cognitive decline: a meta-analysis of prospective studies. Journal of internal medicine 269, 107-117.
  10. Kelly ME, Loughrey D, Lawlor BA et al. (2014) The impact of exercise on the cognitive functioning of healthy older adults: a systematic review and meta-analysis. Ageing Res Rev 16, 12-31.
  11. Young J, Angevaren M, Rusted J et al. (2015) Aerobic exercise to improve cognitive function in older people without known cognitive impairment. The Cochrane database of systematic reviews, CD005381.
  12. Smith JC, Lancaster MA, Nielson KA et al. (2016) Interactive effects of physical activity and APOE-epsilon4 on white matter tract diffusivity in healthy elders. NeuroImage 131, 102-112.
  13. Smith JC, Nielson KA, Woodard JL et al. (2014) Physical activity reduces hippocampal atrophy in elders at genetic risk for Alzheimer's disease. Frontiers in aging neuroscience 6, 61.
  14. Woodard JL, Sugarman MA, Nielson KA et al. (2012) Lifestyle and genetic contributions to cognitive decline and hippocampal structure and function in healthy aging. Current Alzheimer research 9, 436-446.
  15. Head D, Bugg JM, Goate AM et al. (2012) Exercise Engagement as a Moderator of the Effects of APOE Genotype on Amyloid Deposition. Archives of neurology 69, 636-643.
  16. Schuit AJ, Feskens EJ, Launer LJ et al. (2001) Physical activity and cognitive decline, the role of the apolipoprotein e4 allele. Medicine and science in sports and exercise 33, 772-777.
  17. WHO (2010) World Health Organization Physical Acitivity Guidelines 2010, (accessed 09/02/ 2016).
  18. Ekelund U, Steene-Johannessen J, Brown WJ et al. (2016) Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. Lancet.

Nick McKeehan is Assistant Director, Aging and Alzheimer's Prevention at the Alzheimer’s Drug Discovery Foundation. He 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. He received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. Mr. McKeehan also writes about the biotechnology industry for 1st Pitch Life Science.

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