The Effect of Exercise and Diet on the Cognitive Health of Older Adults

Written by Daria Sysoeva | Edited by Kevin Liu

Photo by Juganta Bhitria

Thinking clearly, learning effectively, and remembering information accurately are all signs of great cognitive health [1]. As people grow older, cognitive health tends to slowly decline [2] [3]. More specifically, slower processing speeds, decreased attention, and a decline in memory are common with older age. Research suggests that age-related cognitive health decline may be due to structural changes in the brain, such as a decrease in the size of the hippocampus—the part of the brain that is associated with learning and memory [3]. However, research on older adults suggests that certain lifestyle choices such as exercise and diet may offer protection against age-related cognitive decline. 

Multiple studies show that aerobic exercise, or exercise that promotes oxygen circulation, may improve cognitive health and protect against cognitive decline. In an experiment dividing 120 healthy older adults into two groups—one doing aerobic exercise and one doing non-aerobic exercise—participants in the aerobic exercise group experienced a greater volume increase in their left and right hippocampus compared to the participants in the anaerobic exercise group. Furthermore, the study found that individuals who had greater hippocampal volume performed better on tasks that tested their spatial memory, including tasks like remembering the locations of objects and planning routes to locations [4]. These findings suggest that aerobic exercise may increase hippocampal volume and therefore improve memory function. Furthermore, another study on exercise and cognitive health in mice suggests that there is a hormonal link between exercise and improved cognitive function. The study observed that increased levels of irisin in the blood—a hormone produced by exercise in both humans and mice—is associated with better cognitive performance and reduced inflammation of neurons in the hippocampus [5]. In summary, both of these studies suggest that exercise may improve cognitive health by promoting the physical health of the brain.

 In addition to exercise, a diet rich in vitamins and nutrients may also protect against cognitive decline. More specifically, some research suggests that the nutrients in leafy green vegetables such as Vitamin K and folate are associated with a slower rate of cognitive decline [6]. The M.I.N.D diet, which stands for Mediterranean-DASH Intervention for Neurodegenerative Delay, was designed based on the discovery that leafy green vegetables offered the most protection against cognitive decline compared to other vegetables [7]. A study investigating the effects of the M.I.N.D diet on the cognitive health of older adults found that those who closely adhered to the M.I.N.D. diet scored higher on cognitive assessments over time than those who did not closely follow the diet [7]. However, this association between the M.I.N.D diet and the rate of cognitive decline is still being studied.

It is important to note that the individuals in the M.I.N.D. diet study study were healthy older adults, so these results may not be applicable to adults with preexisting cognitive impairments like dementia. Ultimately, more research needs to be done to show a definite link between cognitive health and lifestyle choices such as exercise and diet.

References:

1. “Cognitive Health and Older Adults.” NIH.gov,https://www.nia.nih.gov/health/cognitive-health-and-older-adults#:~:text=Other%20studies%20have%20shown%20that,nonaerobic%20stretching%20and%20toning%20exercise. Accessed 1 February 2022. 
2. “Healthy Aging.” Memory.UCSF.edu, https://memory.ucsf.edu/symptoms/healthy-aging#:~:text=We%20develop%20many%20thinking%20abilities,in%20mind%20and%20word%2Dfinding. Accessed 1 February 2022.
3. Harada, C.N, Natelson Love, M.C, Triebel, K. (2013). Normal Cognitive Aging, NCBI, 29: 737-752.
4. Erikson, K.I., Voss, M.W., Prakash, R.S., Basak, C., Szabo, A., Chaddock, L., Kim, J.S., Kim, J.S., Heo, S., Alves, H., White, S.M., Wojcicki, T.R., Mailey, E., Vieira V.J., Martina, S.A., Pence, B.D., Woods, J.A., McAuley, E., Kramer, A.F. (2011). Exercise training increases size of hippocampus and improves memory. NCBI,108: 3017-3022. 
5. “Hormone links exercise with cognitive benefits.”NIH.gov, https://www.nih.gov/news-events/nih-research-matters/hormone-links-exercise-cognitive-benefits. Accessed 1 February 2022. 
6. Morris, M.C., Wang, Y., Barnes, L.L., Bennett, D.A., Dawson-Hughes, B., Booth, S.L. (2018). Nutrients and bioactives in green leafy vegetables and cognitive decline: Prospective study. Neurology,90: e214-e222.
7. Morris, M.C., Tangney, C.C., Wang, Y., Sacks, F.M., Barnes, L.L., Bennett, D.A., Aggarwal, N.T. (2015). MIND diet slows cognitive decline with aging. NCBI, 11:1015-1022.