Dementia is the loss of brain function caused by connections between brain cells becoming damaged and dying. Symptoms of dementia may include problems with thinking, problem-solving and memory loss. There are currently 50 million people living with dementia worldwide, and this figure is predicted to rise to 82 million in 2030 (WHO, 2020). In the UK, dementia has overtaken heart disease, stroke and lung cancer and is now the leading cause of death, with 12.8% of all deaths caused by dementia in 2018 (Alzheimer’s Society, 2020).
There is currently no cure for dementia. However, there are behaviours we can engage in to help protect against it, including exercise, eating healthily, stopping smoking, reducing alcohol consumption and training your brain. Neuroscientist Wendy Suzuki, whose TED talk has been viewed over 10 million times, claims that ‘exercise is the most transformative thing you can do for your brain today’, because of both its immediate effects on cognition and long-term protective effects against age-related decline (Suzuki, 2018).
What’s the evidence for exercise and brain health?
Research consistently shows that physically active older adults have a reduced risk of cognitive impairment and dementia compared with those who are sedentary. One study of 2200 elderly Japanese-American men found that those who were sedentary or walked a quarter of a mile or less per day were twice as likely to develop dementia or Alzheimer’s as the men who walked more than two miles per day (Taaffe et al., 2008). Research with over 2000 Chinese elderly adults found that those who exercised regularly had significantly better cognitive functioning and lower rates of dementia at 1-year follow-up than the adults who did not exercise (Lin et al., 2019). Intervention studies have also found that older adults with and without memory impairments who take part in both aerobic and resistance exercise programmes show significant improvements in memory (Angevaren et al., 2008; Busse et al., 2008; Cassilhas et al., 2007).
However, we don’t have to wait until we’re old to experience the brain-boosting effects of exercise – there are immediate effects we can take advantage of too. One study at New York University explored the effects of a single session of vigorous aerobic exercise on cognitive function (Basso et al., 2015). 81 adults aged 18-35 took part in a range of cognitive tests to target the prefrontal cortex, i.e. the area involved in working memory, processing speed, verbal fluency and cognitive inhibition, such as the Stroop Test and Digit Span Test. Half of the participants then cycled on a stationary bike for 60 minutes at 85% of their maximum heart rate, whilst the other half watched an action show on TV for 60 minutes. They then repeated the cognitive tests. The participants who’d taken part in the exercise showed significant improvements in their test performance, and these improvements lasted for up to two hours. However, the participants who’d watched TV showed a decline in their cognitive performance. This research shows just how beneficial a single bout of exercise can be on our ability to use our brains effectively.
And if you’re thinking that exercising at 85% of your maximum heart rate for an hour sounds too much like hard work, then fear not. Other studies have found similar findings even when participants worked at a more moderate 51%-70% of their maximum heart rates for just 30 minutes (Loprinzi & Kane, 2015; Netz et al., 2007). Following exercise, participants demonstrated improved concentration, task-switching and creative thinking. Just imagine how much sharper we could be at work if we did a little bit of exercise in the morning before sitting at our desks?
Why is exercise so good for our brains?
It's not entirely clear why exercise is so beneficial for cognition. However, there are a number of possible reasons that have been suggested in a recent review by Quigley et al. (2020). The first explanation is that physical activity increases blood flow, oxygen and glucose to the brain, which nourishes the brain and therefore makes it work more efficiently. Another explanation is that exercise increases the production of growth factors such as brain-derived neurotrophic factor (BDNF), which helps the brain to create and reorganise new connections. It’s also thought that exercise can reduce levels of stress hormones such as adrenaline and cortisol in the body, which helps the body to relax and improves cognition. Finally, exercise may help to decrease inflammation in the brain. The brain releases anti-inflammatory substances during exercise which counteract the inflammation that occurs with ageing and is associated with cognitive decline.
How can I improve my brain through exercise?
The good news is that these impressive effects of exercise on cognition don’t require a huge time commitment. There’s evidence that just 30 minutes of activity, including some aerobic exercise, at least three times per week can have positive effects on brain function (Suzuki, 2018). And remember, it doesn’t have to be strenuous exercise – much of this research focused on moderate-intensity work, so as long as you’re working at over 50% of your maximum heart rate (which is about the intensity of a brisk walk), you’ll likely be getting brain benefits.
If you’re struggling to feel motivated to exercise at the moment, perhaps try reframing exercise as a way to simultaneously improve your brain power now and reduce your risk of cognitive decline in the future? And try to fit your exercise around your work schedule, so if you’ve got an intense day of work that will require a lot of thinking, maybe try to squeeze in a quick workout before you start to get the most out of your brain!
References
Alzheimer’s Society (2020). The UK’s biggest killer: Why are deaths from dementia on the rise? Retrieved from: https://www.alzheimers.org.uk/blog/research-dementia-UK-biggest-killer-on-the-rise
Angevaren, M., Aufdemkampe, G., Verhaar, H.J., Aleman, A., & Vanhees, L. (2008). Physical activity and enhanced fitness to improve cognitive function in older people without known cognitive impairment. Cochrane Database of Systematic Reviews, 16(3). doi: 10.1002/14651858.CD005381.pub3.
Basso, J., Shang, A., Elman, M., Karmouta, R., & Suzuki, W. (2015). Acute exercise improves prefrontal cortex but not hippocampal function in healthy adults. Journal of the International Neuropsychological Society, 21(10),791-801. DOI: 10.1017/S135561771500106X
Busse, A., L., Filho, W. J., Magaldi, R. M., Coelho, V., A., Melo, A., C., Betoni, R. A., & Santarem, J. M. (2008). Effects of resistance training exercise on cognitive performance in elderly individuals with memory impairment: Results of a controlled trial. Einstein, 6(4), 402-407.
Cassilhas, R.C., Viana, V.A., Grassmann, V., Santos, R.T., Santos, R.F., Tufik, S., & Mello, M.T. (2007). The impact of resistance exercise on the cognitive function of the elderly. Medicine and Science in Sports and Exercise, 39(8),1401-7. doi: 10.1249/mss.0b013e318060111f.
Lin, S., Yang, Y., Qi, Q., Wei, L., Jing, N., Jie, Z., Xia, L., & Shifu, X. (2019) The beneficial effect of physical exercise on cognitive function in a non-dementia aging Chinese population. Frontiers in Aging Neuroscience, 11(238). doi: 10.3389/fnagi.2019.00238
Loprinzi, P.D., & Kane, C.J. (2015). Exercise and cognitive function: A randomized controlled trial examining acute exercise and free-living physical activity and sedentary effects. Mayo Clinic Proceedings, 90(4), 450–460.
Netz, Y., Tomer, R., Axelrad, S., Argov, E., & Inbar, O. (2007). The effect of a single aerobic training session on cognitive flexibility in late middle-aged adults. International Journal of Sports Medicine, 28(1), 82–87.
Quigley, A., MacKay-Lyons, M., & Eskes, G. (2020). Effects of exercise on cognitive performance in older adults: A narrative review of the evidence, possible biological mechanisms, and recommendations for exercise prescription. Journal of Aging Research. https://doi.org/10.1155/2020/1407896
Suzuki, W. (2017, November). The brain-changing benefits of exercise [Video]. TED Conferences. Retrieved from: https://www.ted.com/talks/wendy_suzuki_the_brain_changing_benefits_of_exercise?language=en
Taaffe, D.R., Irie, F., Masaki, K.H., Abbott, R.D., Petrovitch, H., Webster Ross, G., & White, L. R. (2008). Physical activity, physical function, and incident dementia in elderly men: The Honolulu–Asia aging study, The Journals of Gerontology: Series A, 63(5), 529–535, https://doi.org/10.1093/gerona/63.5.529
World Health Organisation (2020). Dementia. Retrieved from: https://www.who.int/news-room/fact-sheets/detail/dementia