Many of us in our 40’s, 50’s and 60’s may have noticed some unwelcome changes in how well we remember things or in how fast our brain works. We may be worried that we are experiencing the first signs of Alzheimer’s disease. Most people do not realize that these unwelcome changes in our cognitive function represent the typical cognitive aging trajectory. The slight decline in cognitive function that we begin to notice in our late 40’s to early 50’s usually becomes steeper with each passing decade [1]. However, there also is enormous variability from person to person in both where an individual starts out on a particular cognitive ability and the rate of decline during our adult years. Some of us worry about being near the bottom of this trajectory as we enter old age. Probably all of us would like to keep our current level of cognitive function for as long as possible.

This leads to the question -- are there things that we can do now to help maintain good cognitive function as we get older? It turns out that we have more control over our cognitive aging process than previously thought. The scientific evidence behind this statement comes from the theory of cognitive reserve. Cognitive reserve is the extent to which we use our brains efficiently and flexibly [2]. In other words, the ability to maximize the brain we have right now.

The theory was developed to explain the following phenomenon: why some people maintain good cognitive function despite having neuropathology in their brains. A study was conducted in which older adults would come to the lab regularly over a number of years and during each visit, they would complete some cognitive tests. Some of these participants very generously donated their brains at death. What the scientists found is that when they did the brain autopsies, some of these older adults had moderate to severe brain pathology that indicated that they had Alzheimer’s disease. Yet these people’s performance on those cognitive tests showed no dysfunction – they performed normally for their age and education level. The researchers wondered how can it be that this subset of people showed no signs of cognitive decline while having pretty significant brain pathology? Yaakov Stern theorized that they had high cognitive reserve – they maximized the brain they had.

Numerous studies support the theory that high cognitive reserve can help compensate for age-related brain changes and even neuropathology that leads to Alzheimer’s disease [1, 3, 4]. Happily for us, we can build up our cognitive reserve by doing certain types of everyday activities, such as hobbies that engage our minds and regular physical exercise.

Indeed, doing activities that boost cognitive reserve are part of the recommended guidelines by the National Institute on Aging and even AARP. These activities can be anything from learning a new skill, taking a class at your local community college, practicing mindfulness, or doing games that require your brain to work quickly [1, 5-11]. To get the cognitive benefit, the activity should be interesting and at least somewhat challenging for you.

Similarly, many studies find that regular exercise can slow down age-related cognitive decline as well as onset of dementia, as assessed by cognitive test performance and/or brain scans [1, 12, 13]. Although cognitive benefits are most pronounced for people who have been long time exercisers [14], sedentary people who complete an exercise program also show improvements in certain aspects of cognition [1, 15]. Some evidence suggest that of all the everyday activities shown to aid cognitive reserve, physical exercise has the highest impact on delaying the onset of dementia [16]. How much exercise is needed to achieve these benefits? The recommended guidelines are 150 minutes per week. If that number seems intimidating, think of it as an approximately 20 minute brisk walk each day.

What’s so exciting about these findings is that they show that we have some control over our cognitive aging trajectory. We can be strategic about our everyday activities today and transform

these cognitively boosting activities into long-term habits. These habits can build up our cognitive reserve and help us maintain good cognitive function in our later years.

*Copyright Images Charles Hamper

Dr. Quinn Kennedy earned a PhD in Psychology and completed postdoctoral training in Cognitive Aging, both at Stanford University. She has over 20 years of research experience in investigating factors that affect older adults’ decision making and performance. Her work has been published in scientific publications including Psychological Science, Psychology of Aging, and Journals of Gerontology. With her collaborators, her work has been featured on Channel 2 news, NPR, The New York Times, San Francisco Chronicle, and Science. Through the Stanford Continuing Studies Program, she teaches “Planning for Your Late-Life Brain: Habits You Can Build Now to Improve Cognitive Function Later.”

References

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[2] Stern, Y., What is cognitive reserve? Theory and research application of the reserve concept. J Int Neuropsychol Soc, 2002. 8(3): p. 448-60.

[3] Colangeli, S., et al., Cognitive Reserve in Healthy Aging and Alzheimer's Disease: A Meta-Analysis of fMRI Studies. Am J Alzheimers Dis Other Demen, 2016. 31(5): p. 443-9.

[4] Stern, Y., Cognitive reserve in ageing and Alzheimer's disease. Lancet Neurol, 2012. 11(11): p. 1006-12.

[5] Park, D.C., et al., The impact of sustained engagement on cognitive function in older adults: the Synapse Project. Psychol Sci, 2014. 25(1): p. 103-12.

[6] Salthouse, T., The processing-speed theory of adult age differences in cognition. Psychological Review, 1996. 10(3): p. 403-428.

[7] Yesavage, J.A., et al., Initial cognitive performance predicts longitudinal aviator performance. Journal of Gerontology Series B: Psychological Science and Social Science, 2011. 66(4): p. 444-53.

[8] Berk, L., et al., Mindfulness Training for People With Dementia and Their Caregivers: Rationale, Current Research, and Future Directions. Front Psychol, 2018. 9: p. 982.

[9] Chan, M.Y., et al., Training Older Adults to Use Tablet Computers: Does It Enhance Cognitive Function? Gerontologist, 2016. 56(3): p. 475-84.

[10] Cheng, S.T., Cognitive Reserve and the Prevention of Dementia: the Role of Physical and Cognitive Activities. Curr Psychiatry Rep, 2016. 18(9): p. 85.

[11] Prakash, R.S., et al., Mindfulness and the aging brain: a proposed paradigm shift. Front Aging Neurosci, 2014. 6: p. 120.

[12] Kramer, A.F. and S. Colcombe, Fitness Effects on the Cognitive Function of Older Adults: A MetaAnalytic Study-Revisited. Perspect Psychol Sci, 2018. 13(2): p. 213-217.

[13] Okonkwo, O.C., et al., Physical activity attenuates age-related biomarker alterations in preclinical AD. Neurology, 2014. 83(19): p. 1753-60.

[14] Horder, H., et al., Midlife cardiovascular fitness and dementia: A 44-year longitudinal population study in women. Neurology, 2018. 90(15): p. e1298-e1305.

[15] Gaitan, J.M., et al., Brain Glucose Metabolism, Cognition, and Cardiorespiratory Fitness Following Exercise Training in Adults at Risk for Alzheimer's Disease. Brain Plast, 2019. 5(1): p. 83-95.