Yoga for a Less-Pain Brain

Neuroscience behind the higher pain tolerance of yogis

Pain, like its counterpart, pleasure, appears in many forms throughout our lives. There is the physical pain of stubbed toes and broken bones, the emotional pain of heartbreak and rejection, the mental pain of depression and anxiety. The hurt we experience is unique, as is our reaction to it. Do we run for pleasure to soothe the pain? Do we look to others, or ourselves, for healing? And given that we have all experienced some pain in our past, how do we reduce the pain that could come in the future?

Let us look to neuroscience for the answers.

Brain and Pain

Our brains can be divided into gray matter, which is the nerve cells themselves, and white matter, which are the connectivity highways that bridge the different regions of the brain. Theoretically, the areas of the brain that are most developed (through habit and training) show denser gray matter, and the areas that speak to one another the most have denser white matter connections. It’s similar to looking at the map of a country and noticing which cities are most populated and which highways are widest and most frequented.

The area of the brain that perceives and processes pain is the insula. Villemure et al. (2013) published a study that found yogis to have greater pain tolerance than non-yogis, and also found that the more experience their subjects had with yoga, the denser the gray matter of their insulas. Yogis also had greater white matter connectivity within their insulas, and reported different coping strategies. While non-yogis tried to either ignore or distract themselves from the pain, yogis were able to relax their bodies and minds and focus on their breathing.

These elegant results show that yoga practice changes the brain in a way that lessens perception of pain. So how does yoga teach us to live less painful lives?

The Yogic Perspective on Pain

The primary foundations of yoga are the Bhagavad Gita and Patanjali’s Yoga Sutras. The Bhagavad Gita, an excerpt from the Indian epic tale Mahabharata, is a dialogue in which Krishna teaches prince Arjun the art of yoga. Yogis are described to “live in peace, alike in cold and heat, pleasure and pain, praise and blame.” This teaching of equanimity is complemented by teachings of detachment (yogis are “free from expectations and attachment”) and compassion (yogis respond “to the joys and sorrows of others as if they were his own”).

Around the same time, circa 200–500BC, Patanjali’s yoga sutras were transcribed. In these aphorisms, Patanjali teaches that ahimsa (nonviolence in word, thought, action), is foundational to the practice of yoga. This commentary speaks to the broader nature of pain:

Himsa, which literally means hurting or harming, is an interaction between two or more participants. The person hurting and the one who is being hurt are both bound by the same element: pain.

The act of hurting is not an isolated phenomenon; rather, it is part of a chain reaction. The perpetrator was probably hurt before and is acting out his pain. The one who is being hurt now will probably in his turn inflict his pain on another… Every time we stop a hurt we create Ahimsa, we create an island of peace in the world…for the good of everyone, we should not allow anyone to harm us.

(Orit Sen-Gupta; A little book of Yoga 2013)

These concepts resonate on an intuitive level. Those who are able to live in equanimity and are able to separate themselves from hurting and being hurt, will be able to lead lives of less pain. But in order to live according to these values, most of us will have to break ingrained emotional habits as well as go against the evolutionary drive to defend our safety and retaliate against those that hurt us.

The physical practice of yoga postures, breathwork, and increased introspection and interoception all work towards helping the yogi witness the habits and defense/attack mechanisms that lead to physical, emotional, and mental pain. Villemure et al. (2013) demonstrated the neurological effects of these yogic techniques.

Study Design

People Studied

The subjects of this study were divided into two groups: 14 yogis and 14 non-yogis, matched for age, gender (5 males per group), education, and exercise other than yoga. The authors chose to exclude regular users of alcohol and/or marijuana, which is an unusual criteria. Most of the yogis had been practicing yoga for 6 to 10 years, and a couple for 15 or 16 years. Some practiced Ashtanga, others Vinyasa, Iyengar, and other styles. The non-yogis had never practiced yoga, meditation, or martial arts. All subjects were paid for their time.

The amount of exercise and yoga practice reported for each group showed a large variability: yogis practiced 8.6 +/- 4.1 hours of yoga and 5.2 +/- 3.1 hours of non-yoga exercise each week; the non-yogis exercised 4.7 +/- 3.5 hours each week. This wide spread is not ideal for neuroimaging data, but perhaps it was difficult to find yogis who don’t smoke and non-yogis who don’t drink.

One of the more interesting aspects of the study are the questions that the authors asked the yogis. All 14 yogis said that they practice yoga to improve their health, and also study yoga philosophy. 6 of the 14 yogis accurately predicted the outcome of the study: regular yoga practice increases pain tolerance outside of yoga practice but the practitioner has increased control and decreased reactivity to it.

Measuring Pain & Brain

In the sciences, pain is often measured via temperature perception, with the understanding that feeling something too hot or too cold on the skin is a painful sensation. The studies are designed for the purpose of understanding pain rather than inflicting pain. In this study, pain was measured in two ways: how long a participant was able to keep their hand in cold water, as well as with an instrument that consistently increased the heat applied to the participant’s forearm. Subjects were able to voluntarily remove their hands from the cold water, as well as stop the application of heat by pressing a button when the sensation felt like stinging or burning. The scientific assumption is that longer tolerance of ice cold water and higher tolerance to heat indicate increased pain tolerance.

This study used a 3.0 T Seimens scanner with a 12 channel head coil to collect structural data, meaning that they were not looking at the brain functioning during pain but looking at the construct of the brain itself independent of activity. From the 10 minute T1 scan, the authors determined the density of gray matter in different brain regions relevant to pain, and from the 15 minute long DTI scan, the authors determined the connectivity between different areas of the brain.

Results

Pain Tolerance

Cold pain tolerance times for yogis were more than twice as long as those for controls, and heat pain threshold was slightly higher in yogis, demonstrating that yogis have higher pain tolerance than non-yogis.

This is specifically physical pain; it is interesting to consider whether this finding implies that yogis also have higher tolerance for mental and emotional distress.

Gray Matter Volume

The authors focused on the gray matter density of the insula, which is known to perceive and process pain.

Left insular gray matter volume was positively correlated with the number of years of yoga practice in yogis. The red triangle shows gray matter volume for the same area of the brains of non-yogis, who have 0 years of yoga practice . This highlights that the longest-term practitioners (>14 years) and the nonpractitioners (0 years) fall onto the opposite ends of the same spectrum.

This demonstrates that the longer one practices yoga, the denser the insula becomes; essentially, more years on the mat leads to more changes in the brain. However, the data sample is a middle-heavy, as you can see in the image above. Most of this study’s yogis have been practicing 6–10 years; just a couple outliers have been practicing over 14 years, and the control group is not too far off from a few of the yogis.

It would have been interesting to note how the duration of daily practice affects this correlation, and whether the style of yoga practiced had any influence.

White Matter Connectivity

“DTI analysis revealed an increased intrainsular connectivity in the left insular cortex that correlated with cold pain tolerance.”

This means that there is more communication within the insulas of yogis, compared to non-yogis. This increased white matter connectivity could be related to the different techniques that yogis have learned for pain management.

Take Home Message

How to best cope with pain

The most powerful message behind this study was neither about the brain or about the perception of pain, but rather: the strategies that yogis use when facing a painful situation.

At the conclusion of the experiment, all 28 participants were asked to describe the strategies they used to keep their hands in the cold water. Their responses fell into 9 categories:

1. focus on breath (3 non-yogis; 10 yogis)
2. observing sensation without reaction (2 non-yogi; 9yogis)
3. conscious relaxation of mind and body (1 non-yogi; 8 yogis)
4. accepting rather than rejecting sensations (1 non-yogi; 8 yogis)
5. using positive imagery (1 non-yogi; 2 yogis)
6. reinterpreting sensation (0 non-yogis; 2 yogis)
7. feeling negative emotions (2 non-yogis; 0 yogis)
8. ignoring the pain (4 non-yogis; 0 yogis)
9. distracting oneself from pain (5 non-yogis; 0 yogis)

Keeping in mind that the yogis demonstrated higher pain tolerance as well as neurological changes that supported their ability to tolerate and manage painful sensations, it is clear that the mental strategies used by these yogis will be beneficial to all who are facing painful situations.

In contrast, those who without yoga practices succumbed to their negative emotions, and tried to ignore and distract themselves. Ultimately, these common strategies are not as effective as breathing, observing, relaxing, and accepting the present conditions.

What each of us can draw from this study, despite its limitations and regardless of whether we practice yoga or meditation, is this: the best ways to handle a painful situation are not fight-or-flight, but rather accept-and-relax.