Imagine all the ways that you could benefit from having a brain that runs quickly and smoothly. Your thought processes would flow that much more efficiently, and mental work would be less, well, work. However, as you get older, you wonder how you'll be able to continue to hold onto your mental acuity.
One approach that continues to gain traction as an antidote to aging involves exercising as a way to maintain the brain's plasticity (ability to adapt and change). In general, the advantages of exercise are supported by researchers who investigate its benefits to counteract the aging process. Aerobic exercise, in which you push your body to reach the so-called “training zone” (80% of your max heart rate) shows the greatest effect on the efficiency of the heart in pumping blood to the body’s tissues. Other forms of exercise are also efficacious in slowing the aging process, such as yoga to promote muscle flexibility and protect from joint damage. However, aerobic exercise remains the gold standard for slowing the otherwise inexorable effects of aging on how efficiently your body can work.
Over the past decade, researchers have explored the idea that if aerobic exercise can benefit the rest of the body, it should also promote healthy brain aging. In part, this effect can be attributed to the impact of greater blood flow to nourish the brain’s basic cells, the neurons. Because neurons depend on oxygen and glucose provided by the blood, they remain healthy when more of these vital substances give them the nourishment they need. Exercise can also stimulate the growth of the dendrites, the parts of the neurons that support learning and memory.
Much of the existing research on the effects on brain aging of exercise and other ways of promoting physical health focuses on the gray matter (GM), the component of brain tissue reflecting integrity of the neurons throughout the areas responsible for learning and memory. As Cameron Clark and colleagues, the authors of one recent study on exercise and brain aging (2019) point out, this “corticocentric myopia” fails to take into account the potential role played by white matter (WM) (2019). It is, they note, the white matter that mediates “connectivity between GM regions, working with information processing areas or organize and allow for the extraordinary range of all possible human behaviors” (p. 1).
To understand why you need your WM to be working as efficiently as possible, think about the last time you needed to pull out of your memory storage the name of a song that you once used to know very well when you switch on the car radio. You’ve got to rush to bring back the song’s name before another song comes on the air that blocks the notes out of your mind. As your mental wheels continue to spin, you wish you could get to that information, but much to your annoyance, find it’s gone out of your head. On other occasions, you wish your brain would work a little more quickly. Perhaps you’re trying to figure out the best detour in order to avoid a traffic tie-up so that you can get where you need to be going without being delayed. You don’t have time to look at your GPS map and have to rely on your own mental map as a guide. Again, if you could just get to the information you need right away, you could save yourself 30 minutes of frustration.
These examples of needing your brain to work as quickly as possible may not be exactly what neuroscientists measure, because WM processing occurs at a far faster speed than would be available to your own conscious mind. The preferred method for examining WM's efficiency involves brain scanning. However, these examples show that speed plus knowledge interact in important ways when you’re trying to maximize your own mental efficiency. Throughout adulthood, age-related changes in the central nervous system can affect both components of cognitive functioning.
In a short-term training study conducted by Clark and his colleagues (2019) on the effects of 6 months of training on WM functioning, the findings actually failed to demonstrate the benefits of involvement in weekly aerobic training. The University of Calgary researchers observed 25 healthy, sedentary adults ranging from 57 to 86 years of age (with an average of 67, 56% male), before and after exercise intervention involving 6 months of 3-4 sessions per week. By the end of that period, the researchers could find no positive effects of this amount of exercise on WM functioning. However, their study was limited by a lack of a control group, an overly wide age range, and a small number of participants studied at less than maximum levels of exertion. The study’s findings imply that it takes more than signing up for a 6-month gym membership to get your WM connections operating at peak levels.
Indeed, exercise is just one component of a program to speed up your brain’s processing time. University of Oxford (UK)’s Thomas Wasenaar and colleagues (2019), noting the widespread interest in slowing age-related declines in WM, point to the longer-term commitment that individuals need to undertake if they are going to change the course of their brain aging. In comparison to the single-sample design used in the exercise training study conducted by Clark and his team, a powerful dataset available to the Oxford researchers made it possible for them to rule out not only potential contributions other than exercise to WM functioning, but also to pinpoint the benefits of each set of modifiers on specific forms of neural integrity. Sample sizes in the studies they included ranged to as high as nearly 4700, and some included a follow-up component.
Evaluating each factor in depth, Wasenaar and his fellow researchers identified the 8 modifiable conditions to avoid and the 4 to promote WM health. Among the 8 brain “no-no’s” are hypertension (high blood pressure), obesity, diabetes, and smoking, all of which also contribute to poor cardiovascular health. Additional contributors to slower WM processing are depressive symptoms, sleep disturbance, depression, and social isolation. The 4 protective factors for WM aging are physical activity, healthy eating habits (preferably the “Mediterranean” diet), mental exercising (keeping cognitively active), and practicing meditation. As you can see, physical exercise is part of the story, but not all of it, as the Clark et al. study seemed to show.
In looking at the specific WM tracts within the brain that are particularly modifiable by lifestyle interventions, Wasenaar and his colleagues note that “most of these tracts have been cited to play a role in various cognitive processes” (p. 65). In other words, protecting your brain’s WM can pay off in preserved if not improved abilities to learn and remember. Those words and names will come faster to you when you keep that WM nourished and supported by your own behavioral interventions.
By looking across multiple studies with large samples and applying suitable statistical controls, the Oxford study avoided the problems of that single exercise intervention study conducted by the Canadian researchers. There is an object lesson here if you’re looking for advice on how to keep your brain as active as possible. Given the complexity of factors that can affect study outcomes, your best bet is to make your own health decisions on studies that incorporate data from a wide range of sources.
To sum up, now that you know the factors to avoid and those to adopt, you can start making those lifestyle interventions that can protect that all-important WM functioning. Your psychological fulfillment depends, in part, on keeping your brain’s machinery working as effectively and efficiently as possible. By taking advantage of the lifestyle modifications suggested by the Wasenaar et al investigation, you’ll up the odds of maintaining your brain health for years to come.
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Clark, C. M., Guadagni, V., Mazerolle, E. L., Hill, M., Hogan, D. B., Pike, G. B., & Poulin, M. J. (2019). Effect of aerobic exercise on white matter microstructure in the aging brain. Behavioural Brain Research, 373. doi: 10.1016/j.bbr.2019.112042
Wassenaar, T. M., Yaffe, K., van der Werf, Y. D., & Sexton, C. E. (2019). Associations between modifiable risk factors and white matter of the aging brain: Insights from diffusion tensor imaging studies. Neurobiology of Aging, 80, 56–70. Doi:10.1016/j.neurobiolaging.2019.04.006