The Doctor Weighs In

Dov Michaeli, MD, PhD explores the impact of aerobic exercise on brain function.

Aerobic exercise and the brain

Now, I want to turn our attention to the brain. Don't worry, I will come back and tell you how this all relates to the titillating findings I wrote about in my last post on the relationship between resveratrol and endurance. But first let's examine the results of a study of the impact of aerobic exercise on brain function.

We know from prior studies that aerobic exercise has beneficial effects on brain function in older adults. For example, compared to elderly people who are sedentary, seniors who engage in regular aerobic exercise demonstrate the following:

• They are more nimble at being able to switch between mental tasks
• Their working memory improves significantly, and
• They can better screen out distractions

In a recent study, reported in the November 2006 issue of the Journal of Gerontology, Dr. Arthur Kramer and his research colleagues delve deeper into the relationship between aerobic exercise and improved brain activity. They used sophisticated brain imaging techniques to demonstrate that these improvements in brain function have an anatomical basis.

They showed that new neurons were formed as a result of aerobic physical activity. This phenomenon is called neurogenesis. Until quite recently, the idea that new neurons could be formed in adults was considered heretical. The researchers noted that exercise-related neurogenesis was especially prone to occur in the frontal lobes of the brain. These are the areas of the brain that are responsible for cognitive functions, such as thinking, working memory, attention.

Furthermore, they showed they showed a large increase in the “white matter” in the brains of exercising seniors. The white matter contains the connections between the neurons (which constitute the “gray matter” of the brain). A particularly important area of white matter is an area called the corpus callosum. The corpus callosum connects the two hemispheres of the brain, right and left. Increased volume of this area explains the observation that exercise increases the integration and coordination of the right and left brains and, thus, increases cognitive efficiency.

Whose brains benefit from aerobic exercise?

The Kramer study included 59 adults, ages 60 to 79. Half of this group exercised (a brisk walk at about 3 miles per hour) 3 hours a week, the other half performed non-aerobic exercises like stretching and toning. Only the aerobic exercisers showed brain benefit.

Since we know that cognitive functions begin a slow decline from about age 40, it may be that adults 40 and elders are the prime beneficiaries of aerobic exercise when it comes to improved brain function.   However, we cannot say definitively that younger people's brains do not benefit from aerobic exercise as that simply not been studied yet.

Resveratrol, aerobics, and the brain: bringing it all together .

As I discussed in my last post, we know that resveratrol does a number of good things with respect to cellular energy metabolism:

• It improves the efficiency of oxygen utilization in cellular organelles called mitochondria
• The improved efficiency of oxygen utilization in mitochondria leads to enhanced ATP production (ATP is the prime energy storage unit for cells)
• Enhanced ATP production facilitates increased physical endurance, at least in mice.

Aerobic exercise, on the other hand, leads to an increased number of cells and therefore, an increased number of mitochondria that produce ATP.  The endpoint is the same as resveratrol.  There is an increased amount of energy, stored as ATP, to fuel various cellular functions.  Thus, enhanced physical endurance and increased brain power.

The problem is, from a practical point of view, very large amounts of red wine must be consumed in order to consume enough resveratrol it to do any good. So, if you think you can drink your way to everlasting happy/healthy life--fuggedaboudit.   You would need to drink hundreds of glasses of red wine every day to consume the required amount of resveratrol. Most likely, rather than live forever with great endurance and expanded brain power,  you’d die of cirrhosis and alcohol-related mental problems.

Let's  consider now what aerobic exercise can do for us. We have now compelling evidence that it is good not only for the body but also for the mind (unlike exessive amounts of red wine). It increases the volume of muscle tissue, the efficiency of mitochondria and their number per cell. Likewise, it increases the number of neurons in the frontal lobes (as well as in the areas of the brain that control motor functions), and it increases the number and efficiency of mitochondria in those neurons.

Here is another  fact: many neurodegenerative diseases, like Alzheimer's disease and Parkinson's disease, are associated with mitochondrial loss of function. Could aerobic exercise slow down the progression of such diseases? We don't know the answer to this question yet, but it is an intriguing possibility.

What is the bottom line with respect to improved mitochondrial energy production?: The best way to develop high functioning mitochondrial energy production is via regular AEROBIC EXERCISE!  It may not be as palatable as drinking lots of red wine, but it is pretty safe, it can be fun, and it improve, not pollutes brain power.