Healthy Heart, Healthy Brain

How exercise might stave off cognitive decline.

Posted Oct 19, 2020

Chris Montgomery on Unsplash
Source: Chris Montgomery on Unsplash

As we pass the half-year mark of the COVID-19 pandemic, many of us still find ourselves stuck at home for the majority of the day. As a result, we might be more sedentary than usual. We might be watching television for longer periods of time, working at our computers, or engaging in social activities that involve video conferencing. This can help us to stay socially engaged, but it further contributes to the more sedentary lifestyle that many of us have become accustomed to during the pandemic. 

This is an important point to highlight because maintaining an active lifestyle is not only important for a healthy body, but it can also assist cognitive health.

camilo jimenez on Unsplash
Source: camilo jimenez on Unsplash

When we learn about the brain, the primary focus typically comprises discussions surrounding neurons and neurochemical signals that contribute to different aspects of cognition such as memory, attention, decision-making, etc. Sometimes we even learn about the transfer of signals to and from different parts of the body. However, an often-overlooked piece of this equation is that, just like any other organ in the body, the blood supply is one of the most important drivers of brain health. Like other organs, the brain requires oxygen in order to properly function. In fact, even though the brain makes up a relatively small portion of our body by weight, it requires approximately one-fifth of the oxygen sent throughout our bodies. 

Recent theory suggests that age-related changes in brain function and cognition might be modifiable with exercise. According to the Scaffolding Theory of Cognitive Aging (STAC; Goh & Park, 2009), exercise can help older adults to engage portions of the brain in new ways, enhancing their task performance. Exercise may even be associated with neurogenesis, or the birth of new cells (Pereira et al., 2007), and it is associated with the preservation of brain cells in key regions like the hippocampus (Firth et al., 2018). This is one of the more important brain regions for memory. This research suggests that normal age-related declines in brain volume might be able to be slowed with exercise, which may benefit cognition. And of course, exercise can also help to keep our vascular system healthier, ensuring that as our heart beats, oxygen-rich blood is able to nourish our brain.

Beyond impacting cognitive abilities directly, exercise can be indirectly beneficial for cognition by impacting other areas of our life. As we highlighted in our last post, sleep is extremely important for our cognitive abilities, and exercise is known to improve sleep quality (Kelley & Kelley, 2017). As a result, exercise may help us achieve some of the cognitive benefits of sleep by making our bodies tired enough to get quality sleep. Also, exercise is known to reduce stress, depression, and anxiety (Mikkelsen et al., 2017), which may also indirectly assist cognition.

At this point, many of us might be thinking, “Well I don’t live an active lifestyle” or, “It might be too late for me.” Fortunately, a recent meta-analysis suggests it is never too late to pick up an exercise routine. Exercise contributes to better executive function and memory in healthy older adults (Sanders et al., 2019). And even older adults diagnosed with cognitive impairments show enhancements in their overall cognitive abilities following short periods of exercise of over several months. So if you’re exercising already, that’s terrific, and your future self will likely benefit; but if you’re not yet living an active lifestyle, you can start today and reap the benefits moving forward. What’s important is that you establish an exercise routine that you can maintain over time.

According to the current guidelines from the Centers for Disease Control and Prevention (CDC), older adults should try to engage in at least 150 minutes of moderate aerobic activity and at least two sessions of muscle-strengthening activity each week. Although 150 minutes per week might seem like a daunting number, when broken down into smaller chunks, this goal might seem more approachable. 

For example, if we engage in aerobic activity for 30 minutes a day, we would be able to meet the CDC’s target after five days. This gives us two whole days of rest in a given week. Or, if it is preferred, we could engage in aerobic activity for 50 minutes a day in order to reach the CDC’s target after 3 days. This would leave us with four days to rest, or engage in muscle strengthening exercises. 

Of course, there are also other potential obstacles to consider when trying to meet this goal. First, what type of aerobic activity is considered “moderate”? As we grow older, many of us might experience pain or be less mobile than our younger selves. This can make extensive movement difficult. Fortunately, according to the CDC, moderate aerobic activity includes any activity where, “you’ll be able to talk, but not sing the words to your favorite song.” This can include brisk walking, mowing the lawn, and for those of us with hip or knee problems, riding a bike can be a great alternative. Other alternatives for those of us with back, hip or knee pain, include water aerobics classes, or swimming laps in a pool.

How do we achieve these exercise goals during a pandemic? Many of us are either used to working out at gyms or walking the length of large indoor spaces like malls or markets. Physical distancing has made this increasingly difficult, because some of the larger indoor spaces are either closed or there are too many people around to successfully physically distance. 

Photo by Scott moon on Unsplash
Source: Photo by Scott moon on Unsplash
Anna Sullivan on Unsplash
Source: Anna Sullivan on Unsplash

This is a great opportunity to get outside! As many parts of the country are beginning to get back to work, early morning outdoor activities might be the best way to get our exercise in while successfully physically distancing. Parks and community paths are great places to engage in these activities. As winter approaches, we might need to move some of our activities back inside. Although it might be somewhat boring, doing laps in the living room, or walking up and down the stairs in our home or apartment, can still provide us with the same aerobic benefit as walking outside or in a larger space. The importance here is to maintain intensity and duration, even while inside. 

We might need to get creative, but even during a pandemic, it is still possible to engage in aerobic exercise and to establish healthy habits. In doing so, in the short term, we can enhance our sleep and maintain our mood. And over the long term, we can maintain our cognition and brain health as we age.

References

Firth, J., Stubbs, B., Vancampfort, D., Schuch, F., Lagopoulos, J., Rosenbaum, S., & Ward, P. B. (2018). Effect of aerobic exercise on hippocampal volume in humans: a systematic review and meta-analysis. Neuroimage, 166, 230-238.

Goh, J. O., & Park, D. C. (2009). Neuroplasticity and cognitive aging: the scaffolding theory of aging and cognition. Restorative neurology and neuroscience, 27(5), 391-403. doi:10.3233/RNN-2009-0493

Kelley, G. A., & Kelley, K. S. (2017). Exercise and sleep: a systematic review of previous meta‐analyses. Journal of Evidence‐Based Medicine, 10(1), 26-36. https://doi.org/10.1111/jebm.12236

Mikkelsen, K., Stojanovska, L., Polenakovic, M., Bosevski, M., & Apostolopoulos, V. (2017). Exercise and mental health. Maturitas, 106, 48-56. https://doi.org/10.1016/j.maturitas.2017.09.003

Pereira, A. C., Huddleston, D. E., Brickman, A. M., Sosunov, A. A., Hen, R., McKhann, G. M., ... & Small, S. A. (2007). An in vivo correlate of exercise-induced neurogenesis in the adult dentate gyrus. Proceedings of the National Academy of Sciences, 104(13), 5638-5643.

Sanders, L. M., Hortobágyi, T., la Bastide-van Gemert, S., van der Zee, E. A., & van Heuvelen, M. J. (2019). Dose-response relationship between exercise and cognitive function in older adults with and without cognitive impairment: a systematic review and meta-analysis. PloS one, 14(1), e0210036.