There is little doubt that our brain changes as we age, with changes in structure that contribute to cognitive decline over time. However, the degree of change is highly variable across individuals in terms of its onset, rate and magnitude. How should we behave, and what should we change to ensure that our brains stay healthy longer? This question of what keeps our brains functioning well is one that should have clear meaning and personal implications for all of us.
In our recent study of 485 cognitively normal older adults, we explored this question in detail through machine-learning analyses that use MRI to look at hundreds of structural features across the brain to compute a “BrainAge.” This is then compared to the number of years the individual has been alive to determine if the brain is younger than expected based on the chronological age. We found that, compared to a control, a six-month exercise intervention was effective at improving cardiovascular fitness and elicited beneficial changes in body composition, mostly in the form of increased lean tissue. But surprisingly, changes in BrainAge over the course of the study were minimal and not related to increased fitness, higher levels of physical activity or changes in sleep. Our findings suggest you cannot exercise your way to a younger brain.
It is worth noting that across our entire cohort, there were individuals who had substantial weight loss, including large amounts of visceral fat. Perhaps individuals who enrolled in our study were motivated to change their lives, or maybe our active control group specifically contributed meaningful lifestyle changes. When we evaluated changes in BrainAge independent of group assignment, we found that changes in fatness, particularly visceral fatness, led to meaningful changes in BrainAge. Individuals who lost visceral fat had brains that were aging more slowly — both compared to others with more visceral fat and in terms of the number of months that had passed. Eureka! We have found the solution to the aging brain: Try to get rid of excess weight and keep it off!
This is of course overly simplistic, as there is no single answer to the challenges of maintaining health over our lifetimes, particularly as we examine something as complex as the brain. However, when our findings are combined with other evidence linking central obesity (in the form of waist circumference) to declines across multiple biological systems, it is clear that being overfat is particularly harmful to health, in both the short and long term.
Given the many important positive changes that occur with improved fitness and increased physical activity, it is tempting to view these as a “fix-everything” solution. This may be particularly true for those of us promoting Exercise Is Medicine®. Encouraging exercise and physical activity to promote health is critical, but there should also be a strong focus on maintaining a healthy body composition, particularly for successful aging and long-term health, including the health of the brain. As such, it is worthwhile to consider and promote the role of “Exercise and Food as Medicine” as we seek to better understand health across multiple complex and interconnected systems.
David Wing, M.S., is the senior manager of the Exercise and Physical Activity Resource Center at the University of California San Diego, where he oversees all aspects of its day-to-day operation. He is also instrumental in design, delivery and dissemination of multiple research studies and educational initiatives. Mr. Wing is completing his Ph.D. at Vrije University Brussels with a focus on the role of fitness, physical activity and body composition on brain health and aging. He is passionate about Exercise Is Medicine® and works with both public health and medical professionals to ensure that physical activity is included as a vital sign and every “patient” is recognized as an athlete.
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