Yoga and Neuroprotection

by Ram

Eugene Lowery, Age 68

In several of my earlier posts, I wrote about yoga’s role in conferring neuroprotection and strengthening the brain (see Mental Exercise, Yoga, and the Perfect Brain). Brain fitness, mental fitness and mental exercise all mean the same and refers to a mentally stimulating task that keeps the brain fit and also wards off mental and physical diseases. Stimulation of the brain can occur in a wide variety of ways. A learning/stimulating environment maintains, builds, and remodels neural network connections. When we learn new things, our brain puts out new neural branches and forms new connections among existing neurons (see 6 Ways to Foster Brain Health with Yoga). Brain plasticity refers to the brain's capacity to rewire itself through experience. Plasticity is the reason why stroke patients re-acquire skills after brain damage. Plasticity also explains how a healthy part of the brain might assume the job of a damaged part. 
Several scientific studies point to the benefits of yoga (asanas, meditation, and pranayama) on brain function, emotional wellbeing, 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, potentially keeping an individual alert and sharp (see The Power of Mental Exercise, Part 1). 
But despite all the evidence and my personal belief about yoga’s positive effect in sustaining mental and emotional well-being, I was still curious about how yoga brought about all these changes. I was interested in knowing if there were truly any structural and functional changes in the brains of individuals who practiced some or all forms of yoga. More specifically, my question was: does yoga of any kind impact the brain or could it be that yoga practitioners are born with different brain structures and volumes that draw them towards yoga? It was a difficult question but could be answered by suitable experiments. So I was very excited when I came across a recent article Neuroprotective effects of yoga practice: age-, experience-, and frequency-dependent plasticity. on yoga’s potential neuroprotective effects that may provide a basis for some or most of its beneficial effects by altering brain structure and function. Before I delve into the article’s finding, let’s revisit certain aspects of neuroanatomy.
Gray Matter: The central nervous system is made up of two types of tissue: the gray matter and the white matter. The gray matter (GM) is a major component of the central nervous system and consists of unmyelinated neurons, neuronal cell bodies, glial cells, synapses, and capillaries. The gray matter includes regions of the brain involved in muscle control, memory, emotions, speech, decision making, and sensory perception, including seeing and hearing. Previous studies have shown that GM declines with age while physical activity and cardiovascular fitness as well as meditation have been associated with increases in GM volume that confers neuro-protection.
Somatosensory Cortex/Superior Parietal Lobule (S1/SPL): This is the area of the brain that predominantly governs the tactile perception. This part of the sensory system consists of a number of different receptors that are involved in regulating touch, temperature, pressure, and pain stimulus. The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals, and is situated above the occipital lobe and behind the frontal lobe. The superior parietal lobule integrates sensory information including spatial sense, navigation, sense of touch, and sense of vision.
Primary Precuneus/Posterior Cingulate Cortex (PCC): The precuneus is part of the superior parietal lobule and is primarily involved with episodic memory. The posterior cingulate cortex area is situated around the midline of the brain and is primarily involved in creating awareness, pain, and episodic memory retrieval. Low functioning of these areas serves as an early sign of Alzheimer’s disease.
Hippocampus: The hippocampus is a major component of the human brain and plays important roles in laying down memory, both short-term and long-term. This area of the brain is also involved in spatial navigation.
Primary Visual Cortex (V1): This area of the brain is responsible for processing visual information and is located in the occipital lobe at the back of the head.
Now to the study on yoga’s potential neuroprotective effects. The study involved 14 experienced yoga practitioners and a control group of 14 physically active people. The control group was individually matched to yogis in terms of gender, age, body mass index, education, and exercise level outside of yoga. The 14 experienced yoga practitioners had an integrated yoga practice that included physical postures, breath control exercises, and concentration/meditation practices including chanting of Sanskrit mantras. These practitioners reported the number of years they had been practicing yoga and the hours/week they devoted to their current personal yoga practice. They also provided information about what proportion of their weekly yoga practice included postures, stand-alone breathing exercises, and meditation, including chanting. All 28 participants underwent one MRI scanning session. The researchers pursued the following three aims:

1. Does changes in the Gray Matter (GM) volume correlate with age in yoga participants and control group?
2. Is there an effect of number of years of yoga practice and hours of weekly yoga practice on GM volume?
3. Does yoga practice differentially affect each area of the brain; and which aspect of the yoga practice had the biggest impact?

The results of the study were very interesting:

• Age-associated decline in GM volume was found to be greater in the control group as opposed to the long-term yoga practice group, suggesting that long-term yoga practice may prevent age-associated decline of GM by strengthening the areas of the brain associated with the gray matter.
• Long-term yoga practice was associated with increases in GM volumes in certain brain areas. In contrast, the ongoing weekly yoga practice increased the volumes of different areas, specifically S1/SPL, PCC, Hippocampus  and V1 areas . It is possible that a daily practice of yoga functionally and structurally affects specific regions of the brain that in turn has a global influence on other brain areas following a sustained practice for several years. 
•  Interestingly, while all forms of yoga practice triggered increases in GM volumes, the subcomponents of the yoga practice differentially affected GM volumes. A combination of postures and meditation contributed the most to the size of the hippocampus, precuneus/PCC, and S1/SPL while the combination of meditation and breath control exercises contributed the most to the primary visual cortex size.
•  The differential influence of asana postures and meditative practices in the brain areas is a further indication that both physical and mental activities have a positive effect on brain structure albeit through changes in separate regions. 
•  Careful analysis of the results suggested that most of the brain changes occurred within the left hemisphere, the part of the brain that is closely related to the parasympathetic response (the Rest and Digest or Relaxation response) that is responsible for nourishment, relaxation, lowering of stress hormones, and optimizing the heart rate and blood pressure. The findings concur with an accumulating body of evidence that a sustained yoga practice modifies the brain more towards a parasympathetic function (see Stress and Your Thought-Behavior Repertoire).
• Daily yoga practice brought changes in brain structure and function that were short lived. In order to further develop and sustain those structural and functional changes, a continuous practice was essential to maintain the improved skill/performance/benefits associated with the brain changes. 

All of the above-mentioned findings provide a neural basis for the beneficial effects of yoga. I can imagine some or many of you may question the small sample size and whether the results need to be taken with a grain of salt. I will address this concern in a future post.Irrespective of the results from the above study, personally, I can see several benefits in myself owing to a regular and sustained yoga practice. I am sure you are also experiencing similar changes, so keep up the practice. And if I can do it successfully, you too can do it to bring greater fulfillment to life.
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