What kinds of exercise are good for brain health?

My interest in reaping the brain health benefits of exercise comes not only from my work as a physical therapist and researcher in this field, but is also driven from a very personal place that unfortunately many of us have witnessed or will witness in our lifetime: a family member with disabling memory loss. In my case, it was seeing the crippling effects Alzheimer's disease had on my grandfather, who passed away from complications related to his condition not so long ago.

What do we know about exercise and brain health?

As of today we know: 1) adults 65 and older are the fastest growing demographic group, reaching 20% of the world population by 2030; and 2) maintaining a sharp mind is a top priority for them. The idea that a healthy mind lives in a healthy body dates back at least 2,000 years, and the benefits of exercise beyond physical health is not a new idea either. The New England Journal of Medicine said this in 1887:

Exercise sustains and improves bodily health by expanding the lungs, quickening the circulation, and promoting growth in muscles and bones. But we know that besides doing all these things, exercise may be made to contribute to brain growth and to the symmetrical development of the mental faculties.

The key question that remains unanswered 130 years since that NEJM article is: what type of exercise should we do, and how much of it is needed to specifically target brain health?

What is the ideal exercise for brain health?

The verdict is still out on an ideal exercise "dose" for brain health, because in short, it's complicated. The long answer is that we are still learning about all the ways in which exercise changes our biology, since not all exercise is created equal, and of course it ultimately depends on who we are, for we are all different. The best exercise program for one person may be quite different from the best one for another. A wealth of studies both in humans and animals have linked the cognitive improvements following exercise (mainly aerobic, such as running and cycling) to the increased capacity of the heart, lungs, and blood to transport oxygen. As a result, generalized brain effects, such as a boost in the number of blood vessels and synapses, increasing brain volume, and decreasing age-related brain atrophy, have all been reported. Aside from this, more localized effects in brain areas related to thinking and problem solving have also been reported, such as a boost in the number of new nerve cells and increases in proteins that help these neurons survive and thrive.

On the other hand, in recent years cognitive improvements have also been demonstrated with other forms of exercise, such as low-intensity mind-body exercises (think some forms of yoga and tai chi) and resistance (i.e., weight) training. Because these exercises either do not work the heart as hard, or do so in a different way, we know less about exactly how they promote these cognitive changes. However, I see this as an encouraging finding for two reasons. First, some sedentary people may need to start with a more gentle routine, eventually building up to more vigorous exercise practices; and second, many people already engage in resistance training for other reasons, such as building stronger muscles and bones.

What can I do now?

The reality is that less than 40% of adults 65 and older engage in at least 150 minutes of physical activity per week, and 20% don't do any type of formal exercise. While these recommendations were drafted by the Centers for Disease Control and Prevention (CDC) for physical health (and are not brain health-specific), a target of 30 daily minutes, five days a week is a reasonable goal, guaranteed to promote physical health. However, we don't yet know if this is the correct dose for brain health. So in the meantime, it seems that since aerobic exercise, resistance training, and mind-body exercises are all associated with evidence specifically supporting benefits for brain health, you should maintain a diverse practice, using these exercises as the building blocks of your regimen.

And where is the science on exercise and brain health headed?

I am confident that through research we will learn the optimal dose of exercise to maintain our brain health, but as of now my educated guess is that the answer won't be a one-size-fits-all "prescription." I also hope that we will discover the answers to many other incredibly intriguing questions related to physical activity and cognitive health, such as: what are the exercises that people will do, and do these lead to any cognitive benefit, on an individual level? I would like to invite you to join this conversation. What type of exercise do you enjoy? Have you noticed any positive effects of exercise on your mental sharpness? Would you consider this experiment: embark on a month-long exercise routine and share with us what results you noticed on your brain health?