08 Dec Is Pain Really All In Your Head? Pain Science Part 2 of 3
What is pain and where does it come from? Pain is an output from the brain, it is a real experience that is always unique to that individual, and is dependent on meaning, which is always context-dependent. It relies on biology, ecology, psychology, and sociology! Furthermore, the output of pain depends on past experiences, perspectives, the internal and external environment, emotions, and predictions. Even though it is an output from the brain, pain can be experienced anywhere in the body regardless of the presence or absence of tissue or structural damage. But is pain really all your head then? In this article, we will break down this simple yet complex question to help you better understand where pain comes from as well as pain science!
Is Pain “All In Your Head”?
Have you ever wondered this after someone has said this to you when you’re in agony and you really don’t care to hear it?! The common takeaway is this means the experience of pain is “all in my head”, the problem is this carries a serious stigma with it and can be detrimental to the person hearing it. To say that pain is all in the brain would be reductionist! Research is showing that the brain is necessary for the pain response, however not sufficient on its own for pain (Thacker 2015). To demonstrate this point, Salomons et al 2016, used brain imaging while a noxious AKA painful stimulus was given to participants with congenital insensitivity to pain; individuals who since birth are unable to feel the sensation of pain. What they found was the brain areas did in fact get activated due to the noxious/painful stimulus, yet subjects still reported no pain experience! This is a difficult phenomenon to explain and never did we imagine we would be saying that pain is more complex than the brain. Therefore, we defer to Manzotti 2016, “In all known cases, neural structures are involved, but so are bodies, the environment, stimuli, tissue damage, past, and future behavior, and social interactions.” AKA, it’s just not that simple to say pain is all in your head, there’s way more to it and the pain you’re experiencing in your body at that specific location is real! Let’s take a look at these factors and their relationship to the pain response!
Is Pain A Symptom Of Prediction?
Prediction: Bayesian Models
The way we perceive the world may not be as it actually is, rather it is the brain’s best prediction that is refined with further sensory evidence AKA everyone may have their own interpretation of reality. This is key to the Bayesian Brain prediction model of pain. Bayes mathematical models state, “the rule updates the likelihood of a given hypothesis (or “prior”), given some evidence, by considering the product of the likelihood and the prior probability of the hypothesis.” This model has helped us learn how other sensations work via prediction factors. For example, “fi i tpe lke ths yr brain cn figure out wht it says”.
A great example is demonstrated via vision. When light enters our eye the image placed on the retina is actually flipped upside down. As this information is sent to processing centers in the brain it re-orients that picture to show us our reality.
A clinical example of this can be demonstrated in the case of cervical pain and the use of “bogus visual feedback” in research done by Harvie et al 2015. The findings of this article concluded, “vision overstated the amount of rotation, pain occurred at 7% less rotation than under conditions of accurate visual feedback, and when vision understated rotation, pain occurred at 6% greater rotation than under conditions of accurate visual feedback.”
Visual pathway Prediction
The ability of the brain to predict relies on its ability to take all incoming sensory data and comparing it to previous experiences, and then quickly making a decision on the output! For example, if we roll our ankle and have a ligament sprain the nociceptors from the periphery sends signals to the brain, the eyes see swelling and send this information, the brain looks into past memories “have we been here before? Am I in a safe environment that this should be my focus?” If yes, then the likely output will be pain. At the same time, if a car is driving at the person with a sprained ankle, the brain changes the output as the key focus is survival. In other words, let’s put the ankle pain issue on the back burner until we are in a safer place that this can be a focus. That injured limping person might perform a great feat of human movement to get out of the way of the car without any ankle pain momentarily! But, once it becomes the focus again, the person just might go back to limping and experiencing pain. Once the brain and body are in a right place with a safe environment, then the person can start working at changing the brain’s perception of the area by safe graded exposure to the injured area with [P]Rehab!
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Is The Brain’s Prediction Of Pain Always Accurate?
We won’t beat around the bush here, the answer is a big fat no. We can all relate to this, we flinch or seize up our entire body when we think something is going to be painful and then laugh it off and relax after it ends up being not so bad! As humans our predictions are not always 100 percent accurate, it can only be as good as the data we are presented with and we will give you examples of this through interesting research that has been completed!
Anatomy Of the Alarm System
Environmental Influences On Neural Predictions
How do our surroundings influence what our brain predicts? According to Stilwell and Harman 2019, “pain is always socially and ecologically grounded” and “it is not just the body’s or brain’s internal processes that shape perception, bodily action and capacity to act based on our social environment are also vital”.
An amazing but truthfully difficult concept to grasp, some examples below may help clear this up a bit!
A novel study by Stefanucci et al 2008 placed subjects on top of a steep hill under 2 conditions; one group had a skateboard while the other had a wooden box. Interestingly, the findings were the skateboard group (afraid because they did not know how to skateboard) predicted the hill to be steeper than the group standing on a wooden box (not afraid, boxes don’t have wheels, no danger perceived). Another interesting study by Steanucci et al 2009, found people perceive doorways to look narrower when they held their arms out to the side, maybe explaining why lifters with “invisible lat syndrome” have “trouble” fitting through doorways.
Lastly, Moseley and Arntz (2007) conducted an experiment pairing noxious stimuli with visual cues that carried implicit meaning—”a red light (semiotically linked with heat and danger) and blue light (semiotically linked with cool and safety).” The results showed pain was rated as more intense, and the stimulus as hotter, when subjects looked at the red-cued stimulus than when they didn’t. Furthermore, pain can be experienced in the presence of visual cues without a noxious stimulus! Bayer and Early 1991 used sham head stimulation as healthy volunteers were able to see the level displayed on the machine and were told it would create a headache. They found pain ratings increased as the sham stimulator intensity was increased! Bayer and Early 1991 concluded, “The results suggest that pain can be produced in the absence of peripheral stimulation.”
This shows us our predictions do not just rely on internal processes but include how we actively engaged with the environment! Let’s take a look further into how our nervous system changes output depending on perception.
Neural Predictions Related to Nutrition
The first example we will discuss over milkshakes! Crum et al 2011 conducted a study to see how the mindset of a particular milkshake would change the physiological response of the hormone ghrelin. For context, this hormone plays a significant role as an indicator of energy insufficiency. It plays a big role in the sensation of hunger, when released it motivates consumption to increase energy. When the right amount of nutrients are reached via food/water intake ghrelin levels are decreased to reduce appetite and give us the sensation of being full. Crum et al 2011 set out to investigate ghrelin levels after consuming an indulgent milkshake and a sensi-shake. Subjects were told, “the goal of the study was to evaluate whether the milkshakes tasted similar and to examine the body’s reaction to the different nutrients (high vs. low fat, high vs. low sugar, etc.)” The milkshakes had two different labels on them, one signifying indulgence and one signifying a health-conscious alternative to an indulgent milkshake.
Here’s the catch, the milkshakes were actually the same! Subjects had one milkshake, ghrelin levels were investigated, and then the process was repeated in a second section with the other milkshake. The findings showed, “mindset of indulgence produced a dramatically steeper decline in ghrelin” and “effect of food consumption on ghrelin may be psychologically mediated, and mindset meaningfully affects physiological responses to food.”
Maybe you’re not a milkshake person, how about Pepsi OR Coca-Cola, beer, or wine? McClure et al 2004 showed that knowing the brand of the soda they were drinking had dramatic influences on expressed behavioral preferences and measured brain responses. In other words, a person that strongly prefers Coca-Cola over Pepsi, when blind to the brand and only going off of taste may rate that the “Pepsi” condition tasted better.
Alright, for the adults, onto beer and wine. Lee et al 2006 showed adding vinegar to beer and labeling it as a “special ingredient” can improve taste ratings if the person is not told the special ingredient is vinegar! Another party trick was demonstrated by Plassmann et al 2008. They showed by increasing the cost of wine but not the actual wine led to increased activation in the pleasure/reward centers of the brain.
So, our predictions on food and drink can be “inaccurate” but what about exercise, medicine, and surgery?
Neural Predictions Related To Exercise
Crum and Langer 2007 helped to answer the question related to exercise. Hopefully, the point has been demonstrated that our prediction relies on all incoming data! One important aspect of this is the communication or language that is used to “prime” us into an output. One example of this is, “No Pain, No Gain.” Depending on how we perceive this we may push through the pain to realize gains, is this the right thing to do? Learn more in our dedicated article below!
READ: IS NO PAIN NO GAIN TRUE?
Crum and Langer 2007 explored this concept of priming by telling female room attendants their work activity is good exercise and fits the recommendation for an active lifestyle. They compared this to a control group that was not told this statement. The findings showed the group primed into believing this was good exercise showed a decrease in weight, blood pressure, body fat, waist-to-hip ratio, and body mass index compared to the control group. The incoming data from a trusted source, once again change the physiological output! Learn how communication plays a role in movement here.
Predictions Based On Language Used In Health Care
Words matter, especially when it comes to pain perception! The language that is used with people can change the brain’s prediction to create negative outcomes. This happens commonly if people are told they are “bone-on-bone” as the doctor points to the X-ray showing the degenerating joint and told to avoid high impact activity. The likely output is fear of movement which leads to a cascade of disabilities and chronic pain. Luckily, we have providers, patients, and researchers who do not accept that solution! We have mounting evidence that “abnormal” findings on imaging are actually extremely common in asymptomatic individuals. For example, Girish et al 2011 found 96 percent of subjects in the study had abnormal findings on ultrasound imaging, however, none of them had pain or discomfort! Read our blog on MRIs for low back pain!
Furthermore, Jarmo et al 2015 showed “progressively implemented high-impact and intensive exercise creates enough stimuli and exerts favorable effects on patellar cartilage quality and physical function in postmenopausal women with mild knee osteoarthritis.” Don’t let “bone-on-bone” scare or stop you, let it fuel you to move more!
Bone on Bone doesn’t happen
Neural Predictions In Medicine And Surgery
This is true in the field of medicine too! (Price et al 2008) People expect and actually get better when taking a name-brand medication even if it’s a sugar pill (Brody 1980 and Barnhill and Miller 2015). Furthermore, the more risky and expensive the surgery, the greater the placebo effect can be. As of recent more and more placebo-based surgical trials have been conducted (Probst et al 2016). One example comes from Sihvoven et al 2018, where they compared pain and functional outcomes at baseline and 2 years follow-up in a population with a degenerative medial meniscus tear. One group underwent arthroscopic surgery, whilst the other underwent placebo surgery. The outcomes for both of these groups were similar! This is also shown in the shoulder joint. Paavola et al 2020 evaluated outcomes in 2 groups; one group received shoulder decompression surgery and one group arthroscopic placebo surgery. The outcomes were no different at 2 or 5 years follow up! They conclude, “The findings…lend further support to existing guidelines that make a strong recommendation against surgery as a treatment for patients with subacromial pain.”
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Back To The Question, “Is Pain All In Your Head?”
The output of pain is always produced in your head aka the brain, BUT it is dependent on complex factors in the environment, therefore we cannot conclude pain is ALL in your head.
The brain will give you a perception of what is happening and is constantly weighing safety vs danger. The alarm system–or the pain signal–will tell your brain WHERE the danger is in your body, the AMOUNT of danger, and the NATURE of the danger (meaning what type of pain: sharp, burning, aching, tingling etc…). If the perception of danger is great enough then the output of pain and protection is created!
How the alarm system works
So, is pain all in your head? Pain is not a measure of how well the tissue is healing, but rather a measure of the need to protect the tissue and how this potential injury plays a role in survival. For example, a minor finger injury will cause more pain in a professional violinist than a professional dancer because finger damage poses a greater threat to the violinist!
Pain may be diminished before the tissue has completely healed. On the other hand, if your pain persists longer than the time it takes for the tissues to heal, then increases in pain are far less likely to relate to the tissue as depicted in this picture. This is because the threshold for this pain signal has been lowered and the issue may no longer be at the tissue! In this case, you may need to train the brain to improve your symptoms. Stay tuned for the next couple of posts to understand how you can train your brain, decrease opioid use, and get out of chronic pain cycles!
About The Author
[P]Rehab Audio Experience Host
[P]Rehab Writer & Content Creator
Dillon is a Sports Physical Therapist, performance coach, and adjunct professor residing in Syracuse, NY whose passion is providing holistic solutions to improve all aspects of human performance. Along with working with clinical athletes across the lifespan, he provides on-field coverage for youth and semi-professional teams. After his undergraduate studies at Syracuse University, he earned his Doctorate in Physical Therapy from SUNY Upstate Medical University. He practices wellness, prevention, and solution-based health care out of Goldwyn & Boyland, PT, and Core Fitness. In his free time, he enjoys family dinners, playing with his dog, and competing as a fitness athlete. Dillon honors the opportunity to join the [P]Rehab guys to influence and educate in a people-first system!