Effects of Sleep and Nutrition on the Aging Brain

By Cameron Anderson, BSc Neuroscience

Sleep

The contributions of proper sleep and nutrition on the aging brain are astoundingly positive. One specific major effect of sleep on the aging brain involves its association with white matter. White matter plays a significant role in the connectivity of the brain, as such, it plays a role in the strength of executive functions: Working memory, behavioural flexibility, and inhibitory control (Altendahl et al., 2020). White matter is composed of myelinated axons, these are important in sending messages across the brain. As such, a declining amount of white matter may result in a diminished ability of the brain to transmit information.

Individuals who experience more quality sleep have been shown to possess healthier, and thicker layers of white matter compared to individuals who have lower amounts of quality sleep (Altendahl et al., 2020; Tsiknia et al., 2023). However, a problem that arises is that older adults tend to sleep less, with a lower sleep quality. While the reasons for this may be multifaceted, a common factor is inappropriate amounts of stress. Toxic amounts of stress can lead to an over-activation of neural circuits. In particular, the cingulo-opercular network, a region where overactivation is associated with sleep loss and affective disorders (Alfini et al., 2020). One possible way to decrease the stimulation of this network, possibly attaining a higher level of sleep quality, is exercise. In the Alfini study, 30 minutes of aerobic exercise was shown to decrease the activity of the cingulo-opercular network, among other benefits. These beneficial effects occurred in a greater degree among older adults who initially displayed greater sleep disturbances (Alfini et al., 2020).

Additionally, although the exact relationship is unclear. Higher levels of sleep quality are consistent with lower levels of beta-amyloid, a hallmark of Alzheimer's disease. It is thought that the brain ‘flushes out’ metabolic waste that may contribute to Alzheimer’s during sleep. As such, individuals with low sleep quality display an increased amount of beta-amyloid, while individuals with higher levels of sleep quality display lower amounts of beta-amyloid (Aribisala et al., 2020).

Nutrition

Another effective way to keep the brain healthy is diet. To summarize, aspects of the ‘Mediterranean diet’ (whole grains, fruits, vegetables, seafood, beans, and nuts) are associated with lower levels of cognitive decline in older adults (Markovic et al., 2021). However, this effect is not limited to the mediterranean diet. Studies have shown that acquiring nutrients that may be missing in diets through supplements or, even acquiring the majority of nutrients through supplements, is positively and significantly correlated with increased cortical thickness, especially in areas of the brain that are vulnerable to Alzheimer’s (Lefèvre-Arbogast et al., 2021).

Omega fatty acids (ω-3 and ω-6) obtained mostly from fish, as well as carotenoids, which are obtained from fruits and vegetables, are two factors of the Mediterranean diet and both display beneficial effects on the brain. Omega fatty acids are important in maintaining the ability of the brain to transmit information. When Omega fatty acids are in low supply, they may be replaced with other fatty acids, hindering the ability of the brain to transmit information. As such, low cognitive performance has been correlated with low levels of Omega fatty acids in the brain (Dong et al., 2020). Dietary intake of carotenoids (the coloured pigments of fruits and vegetables) has been shown to be correlated to the amount of Alzheimer’s hallmarks in the brain. One study, examining the brains of post-mortem patients, found that a higher total carotenoid consumption was associated with lower levels of the hallmarks of Alzheimer’s (Yuan et al., 2021).

References

Altendahl, M., Cotter, D.L., Staffaroni, A.M., Wolf, A., Mumford, P., Cobigo, Y., Casaletto, K., Elahi, F., Ruoff, L., Javed, S., Bettcher, B.M., Fox, E., You, M., Saloner, R., Neylan, T.C., Kramer, J.H., & Walsh, C.M. (2020.) REM sleep is associated with white matter integrity in cognitively health, older adults. PLOS ONE, 15(7): e0235395. https://doi.org/10.1371/journal.pone.0235395

Alfine, A.J., Won, J., Weiss, L.R., Nyhuis, C.C., Shackman, A.J., Spira, A.P., & Smith, J.C. (2020.) Impact of exercise on older adults’ mood is moderated by sleep and mediated by altered brain connectivity. Social Cognitve and Affective Neuroscience, 15(11), 1238-1252. doi:10.1093/scan/nsaa149

Aribisala, B.S., Riha, R.L., Valdes Hernandez, M., Muñoz Maniega, S., Cox, S., Radakovic, R., Taylor, A., Pattie, A., Corley, J., Redmond, P., Bastin, M.E., Starr, J., Deary, I., & Wardlaw, J.M. (2020.) Sleep and brain morphological changes in the eighth decade of life. Sleep Medicine, 65, 152-158. https://doi.org/10.1016/j.sleep.2019.07.015

Dong, X., Li, S., Chen, J., Li, Y., Wu, Y, & Zhang, D. (2020.) Association of dietary ω-3 and ω-6 fatty acids intake with cognitive performance in older adults: National Health and nutrition examination Survey (NHANES) 2011–2014. Nutrition Journal, 19. https://doi.org/10.1186/s12937-020-00547-7

Lefèvre-Arbogast, S., Dhana, K., Aggarwal, N.T., Zhang, S., Agarwal, P., Liu, X., Laranjo, N., Carey, V., Sacks, F., Barnes, L.L., & Arfanakis, K. (2021.) Vitamin D Intake and Brain Cortical Thickness in Community-Dwelling Overweight Older Adults: A Cross-Sectional Study. The Journal of Nutrition, 151(9), 2760-2767. https://doi.org/10.1093/jn/nxab168

Markovic, S.J., Fitzgerald, M., Peiffer, J.J., Scott, B.R., Rainey-Smith, S.R., Sohrabi, H.R., & Brown, B.M. (2021.) The impact of exercise, sleep, and diet on neurocognitive recovery from mild traumatic brain injury in older adults: A narrative review. Ageing Research Reviews, 68, 101322. https://doi.org/10.1016/j.arr.2021.101322

Tsikinia, A.A., Parada, H., Banks, S.J., & Reas, E.T. (2023.) Sleep quality and sleep duration predict brain microstructure among community-dwelling older adults. Neurobiology of Aging, 125, 90-97. https://doi.org/10.1016/j.neurobiolaging.2023.02.001

Yuan, C., Chen, H., Wang, Y., Schneider, J.A., Willett, W.C., & Morris, M.C. (2021.) Dietary carotenoids related to risk of incident Alzheimer dementia (AD) and brain AD neuropathology: a community-based cohort of older adults. The American Journal of Clinical Nutrition, 113(1), 200-208. https://doi.org/10.1093/ajcn/nqaa303