How Exercise Fosters Brain Health

by Ram

Fostering Brain Health & Balance by Melina Meza

The concept “use it or lose it” for physical abilities applies to the brain as well. As long as we engage our brain in stimulatory activities, the brain actively grows and rewires itself in response to the stimulation and new learning. Brain fitness, mental fitness, and mental exercise all mean the same thing: it is the act of performing a mentally stimulating task that keeps the brain resilient. Additionally, it is well known that physical exercise can also either prevent or delay the onset of mental and physical diseases. Furthermore, age-associated memory loss can be prevented by physical activity/exercise as well. Engaging in regular aerobic activity leads to structural changes in the brain resulting in improved cognition. 

Physical exercise increases nerve branching and in some cases triggers regeneration of new nerve cells, especially in the memory centers of the brain. Owing to the structural changes, physical exercises help an individual to learn new things and to be more alert and attentive. Scientists believe that physical exercises trigger increased blood flow to the brain. The greater the blood flow, the more oxygen and other important nutrients that reach the brain. This may explain the cognitive improvements associated with exercise. Physical exercises will also help maintain optimal blood pressure, control diabetes, and lower cholesterol levels, all of which are potential mental risk factors.

Personally, my day doesn't feel right if I do not perform some kind of a physical activity. There are days when I feel so tired and my brain refuses to work smoothly towards the end of the day. Being aware of the fact that physical exercise is not only important for my body's health but it also helps the brain stay sharp, I force myself to go for a workout to the local gym. The same antidepressant-like effects kick in after exercising for just 20 minutes. I consider that a regular, well-rounded asana practice is also an excellent form of physical exercise, fostering strength, flexibility, balance, and agility. Several scientific studies point to the benefits of yoga on brain function, emotional well-being, and general mental acuity. Yoga increases brain chemicals such as endorphins and enkephalins that contribute to a feel-good response and ward off mental stress. It is akin to stimulating the brain in a positive way, which results in optimal brain function, which can keep an individual alert and sharp. While a trove of scientific studies supports the idea that physical exercise (including yoga) help the brain grow stronger, exactly how exercise alters and improves the brain was unclear until now. 

A recent study Exercise promotes the expression of brain derived neurotrophic factor (BDNF) through the action of the ketone body β-hydroxybutyrate provides an interesting answer linking physical activity to brain improvement. Although the study was not in humans but in mice, it appears that similar mechanisms may be manifesting inside human brains as well, thus giving additional credence to the study. For several years, scientists and neurophysiologists have understood that the brains of animals and humans who regularly exercise are different than those who are sedentary. Studies conducted in rodents clearly show that exercise triggers neurogenesis, that is, it induces the creation of many new cells in the hippocampus, the area of the brain that is responsible for memory and learning. Exercise also strengthens the growth and branching of these fragile, newborn neurons. Turns out that physical exercise boosts the production of a nerve-stimulating factor called BDNF (brain-derived nerve growth factor). BDNF supports the survival of existing neurons, and stimulates the growth and differentiation of new neurons. It also strengthens nerve-nerve communication. Although the vast majority of neurons in the mammalian brain are formed during birth, some regions of the adult brain retain the ability to grow new neurons in a process known as neurogenesis. Thus, BDNF plays an important role in neurogenesis. The more BDNF there is, the stronger the neuron and the nerve-nerve communication, making the brain more resilient. 

The question these researchers in this particular study asked was, how exactly does exercise turn on the production of BDNF? To get to the bottom of this question, the researchers divided mice into two groups: one group of mice had the luxury of having a running wheel put into their cages and the other was housed in cages without the running wheel. Rodents have a specific affinity for running wheels and can keep themselves busy for long hours on them. The group with the running wheels did just that, running very often and covering several miles a day. The group in cages without the running wheels was comparatively sedentary. After four weeks, the scientists measured the BDNF levels in the hippocampus of both groups of animals. As expected, BDNF protein levels were much higher in the brains of the runner mice compared to the sedentary mice. 

To better understand why the runners had more BDNF protein, the researchers used sophisticated testing methods and closely examined the BDNF gene in the animals’ DNA. To their amazement, they noticed that the BDNF gene was more actively synthesizing the BDNF protein among the animals that exercised than those that did not. How did this happen? Let me use an analogy to better understand the mechanism. To get to the heart of the artichoke, one needs to peel the outer layer by layer to reveal its core. Similarly, the BDNF gene is encapsulated by clusters of a particular molecule called HDAC, which can prevent the BDNF gene from receiving messages from the brain or body to synthesize the protein. In the non-exercising mice, these HDAC molecules clustered so densely over the BDNF gene that messages from the body and brain got blocked and could not reach the gene to activate it. As a result, the BDNF gene of the sedentary mice was subdued, pumping out very little BDNF protein. In contrast, among the runners, the physical activity literally peeled of the dense HDAC molecules covering the BDNF gene, thus exposing the gene to the messages from the brain/body telling it to turn on and produce the BDNF protein. 

Additionally, the physical exercise also triggered the production of ketones, which are a byproduct of the breakdown of fat. During strenuous exercise, the body relies in part on fat for fuel, thus ending up creating ketones, some of which migrate to the brain. Ketones act like molecular scissors, and in this case ripped off the HDAC molecules covering the BDNF gene making it easy for the BDNF gene to now make the BDNF protein. None of this occurred in the brains of the sedentary mice suggesting the importance of physical exercise. 

The question is: does a similar phenomenon happens in humans? While it is still not known whether the same mechanisms that occur in mice occur in our own brains when we exercise, undoubtedly we have more BDNF in our bodies after we exercise. Yoga is also known to increase the levels of BDNF protein (see Age-related changes in cardiovascular system, autonomic functions, and levels of BDNF of healthy active males: role of yogic practice). We also create ketones when we exercise that migrate to our brains to elicit its favorable effects. Thus, physical exercise together with the ketone bodies arising out of those exercises turn on the BDNF gene that in turn triggers the production of BDNF protein, which sustains and protects the neurons and nerve-nerve communication. 

So I’d just say that it is a very good idea to just keep moving or doing your regular yoga sessions.

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