The Psychobiology of Pain: How does pain work, and how could somatic practice help?

Sarah Charles

Sarah Charles preparing blood for analysis
Photo by Sarah Charles (2019)

Highlighting the biological and psychological mechanisms that lead to pain can help provide some insight into how movement in general, and somatic practice in particular, might help those living with pain.

One of my major interests is the “science of emotion”, with a particular fascination with how taking part in certain behaviours (music listening/performance, dance, ritual, etc.) might affect emotion. I am interested in the chemistry of the brain and finding out which chemicals play key roles in our emotions.

In my work, one set of brain chemicals that I have studied in-depth are called “opioids”. This is a word many people may have heard of, especially those living with chronic pain. This is because of the prominence of opioid-based pain medications that are often prescribed to those with pain (e.g. codeine and morphine). However, your body naturally produces opioids, too. The best-known of these naturally occurring opioids (and the body’s main codeine-/morphine-like opioid) is named “beta-endorphin”, sometimes named “endorphins”. These endorphins give you the rush known as the “runner’s high” after exercise (Boecker et al., 2008).  As a consequence of studying opioids, I ended up researching pain, and how the activities mentioned above may alter the pain experience.

Mechanics of Pain

Why We Have Pain

Pain is, evolutionarily speaking, a useful tool for all animals (including humans) to let us be aware of when a part of our body may be damaged in some way (be it via heat, pressure, or some other damage). There is extensive literature on the purpose of pain for mammals in general, as well as humans in particular.  Some pain is a necessary component of a functional life: we need to know what is dangerous and what is not so that we can react accordingly.

Acute Pain experience

Pain is an incredibly complex phenomenon, with no one chemical being the “be-all and end-all” of pain. However, opioids do play an important role in the pain experience. Consequently, many medical professionals will use opioid-based medication as a way to help alleviate pain for those experiencing it. This is because opioids alter the point at which you start to feel pain (pain threshold; Fillingim et al., 2005; Hagelberg et al., 2012; Huang et al., 2008; Kialka et al., 2016), helping lessen the pain experience. Our body naturally releases small amounts of endorphins in response to pain to help lessen the intensity of pain, but sometimes this is not enough. This is why you will often be given morphine or a similar pain killer after major surgery or a major injury: this will increase your threshold to pain so that the same strength of painful stimuli (e.g., the broken bone, or the surgery wound) doesn’t feel as intense (see Graph 1, below).

Graph 1. Dummy data depicting the perception of acute pain with different strength of painful stimulus under normal conditions (blue) or if the person has been given an opioid drug (red). An opioid drug increases the strength a painful stimulus must be for the onset of pain to occur. After the onset of pain occurs, pain intensity can still increase like normal.

If you are only exposed to your body’s endorphins, they do not seem to lose effectiveness with time/age. i.e., the human body does not become more resistant to your natural pain killers. If it did, all humans would become hyper-sensitive to pain.  Using this logic, for many years, it was thought that the same principle shown in Graph 1 could be applied to chronic pain. There was, at the time, no major reason to believe that opioids would become less effective at treating pain over time. Consequently, many people living with chronic pain were prescribed opioid medications to help alleviate their symptoms.

However, when it comes to chronic pain, opioid medication is now acknowledged to not be nearly as useful as for acute pain (Ballantyne, 2017). This is because, much like with many drugs, consistent use of strong opioids (i.e., codeine, morphine, heroin etc.) can lead your body to become less responsive to the effects of opioids. This includes becoming less responsive to even your body’s endorphins.  This means that, over time, consistent use of opioid drugs can actually lead to a greater sensitivity to pain (Mao 2002, 2006; DuPen et al., 2007; Higgins et al., 2019), as your body’s endorphins are no longer enough to increase your pain threshold to a functional level themselves. Graph 2 shows this visually. This is a major reason why the prescription of opioid drugs is not always the “go-to” treatment for all people with chronic pain issues (also, more consideration is given to the other side-effects of opioid drugs, and their addictive properties).

Graph 2. Dummy data depicting the perception of pain with different strength of painful stimulus under normal conditions (blue) or if the person has been on long-term opioid treatment (red). Long-term opioid treatment lowers the strength a painful stimulus needs to be before you experience it as pain. After the onset of pain occurs, pain intensity still increases like normal.

Pain and Somatic Practice

“So?” I hear you ask, “What does this have to do with movement or somatic practice?”

Somatic practice is a guided practice, where a practitioner works alongside their client to help them become aware of their body, and the sensations their body is experiencing. Somatic practice is often performed in a one-on-one setting and, often, to help the client become aware of their bodily sensations, this involves some form of touch. It has long been shown that social touch (such as one-on-one touch that occurs in somatic practice) changes the way the opioid system activates in humans (Dunbar, 2010; Nummenmaa et al., 2016). It usually leads to the release of opioids in a way that leads to positive emotions and increases in pain threshold (Nummenmaa et al., 2016).

Similarly, many of topics covered elsewhere on this blog, such as synchronised movement (Lang et al., 2017; Mogan et al., 2017) in the form of dance (Tarr et al., 2015, 2017) and yoga (Suri et al., 2017; Yadav et al., 2012) also cause the release of endorphins. Given that yoga can be included as a form of somatic practice, and that dance is often incorporated in the work of many somatic practitioners, it is no surprise that many of them have seen positive outcomes in their client’s pain experiences after conducting sessions.

Concluding remarks

In summary, pain is a very normal, and useful, part of the body’s response to being damaged in some way. The body’s opioid system plays a key role in pain perception. While long-term opioid drug use can lead to issues with increase pain sensitivity, the body’s natural opioids do not lead to increased pain sensitivity. So, those who suffer with chronic pain may find some benefit in taking part in activities that help their body release endorphins, such as yoga, dance or other forms of somatic practice.


References

Ballantyne, J. C. (2017). Opioids for the treatment of chronic pain: mistakes made, lessons learned, and future directions. Anesthesia & Analgesia125(5), 1769-1778.

Boecker, H., Sprenger, T., Spilker, M. E., Henriksen, G., Koppenhoefer, M., Wagner, K. J., Valet, M., Berthele, A., & Tolle, T. R. (2008). The runner’s high: opioidergic mechanisms in the human brain. Cerebral cortex, 18(11), 2523-2531.

Dunbar, R. I. (2010). The social role of touch in humans and primates: behavioural function and neurobiological mechanisms. Neuroscience & Biobehavioral Reviews34(2), 260-268.

DuPen, A., Shen, D., & Ersek, M. (2007). Mechanisms of opioid-induced tolerance and hyperalgesia. Pain Management Nursing8(3), 113-121.

Fillingim, R. B., Kaplan, L., Staud, R., Ness, T. J., Glover, T. L., Campbell, C. M., … & Wallace, M. R. (2005). The A118G single nucleotide polymorphism of the μ-opioid receptor gene (OPRM1) is associated with pressure pain sensitivity in humans. The Journal of Pain6(3), 159-167.

Hagelberg, N., Aalto, S., Tuominen, L., Pesonen, U., Någren, K., Hietala, J., … & Martikainen, I. K. (2012). Striatal μ-opioid receptor availability predicts cold pressor pain threshold in healthy human subjects. Neuroscience letters521(1), 11-14.

Higgins, C., Smith, B. H., & Matthews, K. (2019). Evidence of opioid-induced hyperalgesia in clinical populations after chronic opioid exposure: a systematic review and meta-analysis. British journal of anaesthesia122(6), e114-e126.

Huang, C. J., Liu, H. F., Su, N. Y., Hsu, Y. W., Yang, C. H., Chen, C. C., & Tsai, P. S. (2008). Association between human opioid receptor genes polymorphisms and pressure pain sensitivity in females. Anaesthesia63(12), 1288-1295.

Kialka, M., Milewicz, T., Mrozinska, S., Sztefko, K., Rogatko, I., & Majewska, R. (2016, May). Pressure pain threshold and [beta]-endorphins plasma level are higher in lean polycystic ovary syndrome women. In 18th European Congress of Endocrinology (Vol. 41). BioScientifica.

Lang, M., Bahna, V., Shaver, J. H., Reddish, P., & Xygalatas, D. (2017). Sync to link: Endorphin-mediated synchrony effects on cooperation. Biological Psychology127, 191-197.

Mao, J. (2002). Opioid-induced abnormal pain sensitivity: implications in clinical opioid therapy. Pain100(3), 213-217.

Mao, J. (2006). Opioid-induced abnormal pain sensitivity. Current pain and headache reports10(1), 67-70.

Mogan, R., Fischer, R., & Bulbulia, J. A. (2017). To be in synchrony or not? A meta-analysis of synchrony’s effects on behavior, perception, cognition and affect. Journal of Experimental Social Psychology72, 13-20.

Nummenmaa, L., Tuominen, L., Dunbar, R., Hirvonen, J., Manninen, S., Arponen, E., … & Sams, M. (2016). Social touch modulates endogenous μ-opioid system activity in humans. NeuroImage138, 242-247.

Suri, M., Sharma, R., & Saini, N. (2017). Neuro-physiological correlation between yoga, pain and endorphins. International Journal of Adapted Physical Education and Yoga.

Tarr, B., Launay, J., Cohen, E., & Dunbar, R. (2015). Synchrony and exertion during dance independently raise pain threshold and encourage social bonding. Biology letters11(10), 20150767.

Tarr, B., Launay, J., Benson, C., & Dunbar, R. I. (2017). Naltrexone blocks endorphins released when dancing in synchrony. Adaptive Human Behavior and Physiology3(3), 241-254.

Yadav, R. K., Magan, D., Mehta, N., Sharma, R., & Mahapatra, S. C. (2012). Efficacy of a short-term yoga-based lifestyle intervention in reducing stress and inflammation: preliminary results. The journal of alternative and complementary medicine, 18(7), 662-667.


Sarah Charles is a psychology and neuroscience researcher interested in exploring the neurochemical mechanisms underlying cognition and behaviour. She has taught at Coventry University, Nottingham Trent University and currently works as a research associate at King’s College, London.

This blog does not provide medical advice and the views and opinions expressed in each blog post belong to and are the responsibility of the author(s) of the blog posts. Any information that you use is at your own risk.  You should always consult with a health care professional about any general or specific health concerns.

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