I have chronic pain from my stroke, all day, every day, so I know a thing or two. But I wanted to know more. So it’s research time again!
The Bayesian Brain concept is named after the 18th-century mathematician Thomas Bayes. Key aspects related to Thomas Bayes and the “Bayesian Brain”:
- This theorem provides a mathematical method to update the probability of a hypothesis based on new evidence.
- This hypothesis suggests that the brain uses a similar probabilistic process to infer the causes of sensory inputs and make predictions about the world.
- The core idea is that the brain operates like an inferential machine (IFM) and is a branch of statistics that uses sampled data to draw conclusions or make predictions about a larger population, constantly updating its beliefs and predictions based on incoming information, in a manner consistent with Bayesian principles. (IFM is generally considered more powerful and may be better suited for deeper tissue pain, while TENS machines are less).
Even if you break a bone or injure a muscle, your brain is what creates the sensation of pain. Pain signals travel from the body to the spinal cord and then to the brain because the brain controls how you experience it.
Just because pain is processed in the brain doesn’t mean it’s not real. You may feel pain even without clear damage, or you may have trouble communicating or locating the pain, even though it’s intense.
Sometimes the brain keeps producing pain long after the original injury is gone. This is common in nerve damage or people with long-term injuries or surgeries. In those cases, the brain’s pain system becomes overactive like an alarm that won’t cease.
Pain typically starts with actual tissue damage or inflammation that activates specialized nerve receptors called nociceptors. These send signals through your nervous system to your brain. Your brain interprets these signals and creates the conscious experience of pain. The brain can amplify, diminish, or even generate pain sensations based on various factors like attention, emotions, past experiences, and expectations.
Things like stress, anxiety, and fear can genuinely increase pain intensity. Conversely, distraction, relaxation, and positive emotions can reduce it. These psychological states trigger real neurochemical changes that affect pain processing.
The nervous system can become hypersensitive In conditions like fibromyalgia or chronic fatigue syndrome, creating real pain even without ongoing tissue damage. The pain is absolutely real to the person experiencing it. How we express and cope with pain is influenced by cultural background, social support, and learned behaviors.
Proponents of the “pain is in your head” theory include several current researchers and pain specialists who emphasize the brain’s central role in pain perception. Pain experts who argue that “pain is constructed entirely in the brain” along with clarifying this doesn’t make the pain less real.
Emotions like humiliation, fear and unpredictability all turn up the volume on pain. Pain perception is “a subjective experience, influenced by complex interactions of biological, psychological, and social factors” (Pain Theory – StatPearls – NCBI Bookshelf).
Pain is the body’s way of telling us there is an injury, and we need to do something about it to ensure that healing occurs. An important consideration when talking about pain is the fact that one patient’s pain is not the same as another patient’s pain, even if they have experienced similar injuries.
There are reports that the cost for chronic pain patients in the US is anywhere between 560 to 635 billion dollars annually. Furthermore, increased opioid prescription and use, until opioid addiction in the United States and Canada is a dramatic phenomenon that has been responsible for up to 70.000 drug overdose deaths in 2017.
The underlying foundations of pain perception (and its processing) represent a field of study that has interested researchers for centuries. The theory goes back to the Athenian philosopher Plato (c. 428 to 347 B.C.) who in his work Timaeus, defined pain not as a unique experience, but as an ’emotion’ that occurs when the stimulus is intense and lasting.
The oldest explanation for why pain manifested in specific populations was rooted in religious beliefs. Throughout history, religious ideologies have had a substantial influence on people’s thoughts and actions. As a result, the majority of people believed that pain was the consequence of committing immoral acts. There was also a belief that the suffering they endured was the individual’s way to repent for these sins.
Although this belief remained popular up until the nineteenth century, this was not due to the lack of other available theories. One of the first alternative scientific pain theories was bravely introduced in 1644 by the French philosopher Renee Descartes (1596-1650). This theory has the name in current literature as the Cartesian Dualism Theory of pain which is pain was a mutually exclusive phenomenon. Pain could be a result of physical injury or psychological injury. However, the two types of injury did not influence each other, and at no point were they to combine and create a synergistic effect on pain, hence making pain a mutually exclusive entity.
Many scientists continued to do research long after Descartes proposed the dualistic theory of pain. However, it wasn’t until 1811 that another well-known pain theory came onto the scene. This theory, initially presented by Charles Bell (1774–1842), is referred to as the Specificity Theory.
This theory is similar to Descartes’ dualistic approach to pain in the way that it delineates different types of sensations to different pathways. Bell also thought that the brain was not the unvarying object that Descartes believed it was, but instead a complex structure with various factors.
In 1894, Maximillian von Frey made another critical addition to the Specificity Theory that served to advance the concept. This contribution to the theory was the discovery of the four separate somatosensory modalities found throughout the body. These sensations include cold, pain, heat, and touch. This concept correlates well with previous research done regarding this theory of pain, which served to say once again the presence of distinct pathways for different sensations.
Following the Specificity Theory, there were a handful of other philosophies introduced regarding the sensation of pain. Of these philosophies, the Pattern Theory of pain has the greatest coverage in the scientific literature. The American psychologist John Paul Nafe (1888-1970) presented this theory in 1929. The ideas contained in the Pattern Theory were directly opposite to the ideas suggested in the Specificity Theory in regards to sensation.
According to Nafe, the brain then takes this pattern and deciphers it. Depending on which pattern the brain reads, correlates with the sensation felt. At the time of its introduction, the Pattern Theory gained significant popularity among many researchers. However, through further research and the discovery of unique receptors for each type of sensation, it can be stated with certainty, that this theory is an inaccurate explanation for how we feel pain.
Current research has suggested that a negative state of mind serves to magnify the intensity of the signals sent to the brain as well. For example, somebody who is depressed has a “gate” that is open more often, allowing more signals to get through, increasing the likelihood that an individual will experience pain from an otherwise normal stimulus. Also, there are reports that certain unhealthy lifestyle choices will also result in an “open gate,” which in turn leads to pain that is disproportionate to the stimulus.
The Gate Control Theory has proven to be one of the most significant contributions to the study of pain throughout history. Some scientists introduced to the study of pain are still utilized by researchers today. Even though this theory initiated the idea that pain wasn’t solely a result of physical injury but rather a complex experience, influenced by cognitive and emotional factors, but there was still additional research needed to understand the mechanisms and examination of pain completely.
About thirty years after introducing the Gate Control Theory of pain, Ronald Melzack introduced another model that contributed to the explanation of how and why people feel pain. Until the mid-1900s, most theories of pain implied that this experience was exclusively due to an injury that had occurred somewhere in the body.
The mindset was that if a person suffered an injury, whether it be through trauma, infection, or disease, a signal would transmit to the brain which would, in turn, result in the sensation of pain. Although Melzack had contributed to these previous theories, it was his exposure to amputees that were experiencing phantom limb pain in well-healed areas that prompted his questions into this more accurate philosophy of pain. The theory he proposed is known as the Neuromatrix Model of pain.
This philosophy suggests that it is the central nervous system that is responsible for eliciting painful sensations. The Neuromatrix Model denotes that there are four components within the central nervous system responsible for creating pain. The four components are the body-self neuromatrix, the cyclic processing and fusion of signals, the guard of the neural hub, and the activation of the neuromatrix.
The signal that these areas of the central nervous system work together to create is responsible for allowing an individual to feel pain, and Melzack referred to as the “neurosignature.” This theory states that input coming in from the fringe can initiate or influence the neurosignature, but these peripheral signals cannot create a neurosignature of their own. For example, hyperactivity of the stress response is when an individual exposed to increased levels of stress experiences a higher level of pain.
The Biopsychosocial Model provides the most comprehensive explanation behind the cause of pain. This specific theory of pain contemplates that pain is the result of complex interactions between biological, psychological, and sociological factors, and any theory which fails to include all of these three elements of pain fails to provide an accurate explanation for why an individual is experiencing pain.
It wasn’t until 1977 that the Biopsychosocial Model was scientifically suggested as an explanation for the examination of some medical conditions. George Engle claimed that to treat disease sufficiently, one must consider the intricate concepts and manage the whole patient instead of focusing on a single issue. This account offers the human body cannot be divided into separate categories when considering treatment options.
Nociception is the signal that is sent to the brain from the periphery to alert the body that there is some degree of injury or tissue damage. Pain, on the other hand, is the subjective experience that occurs after the brain has processed the nociceptive input. The last two components of pain that comes along with consideration should be given to the person who is suffering and pain behaviors.
The thinking is that suffering is an individual’s emotional response to pain behaviors are the actions that people carry out in response to the experience of pain. It can be either conscious or subconscious. These elements of pain account for the biological, psychological, and sociological factors that can create or influence an individual’s experience with pain. Failing to consider any one of these four elements when determining the cause or establishing a management plan could be a consideration as inadequate assessment.
This kind of treatment focuses not on curing the problem but instead on gaining back maximal functional capacity. Certain specialties need to be included in a biopsychosocial treatment plan when managing patients with chronic pain to achieve this goal. These mandatory specialties include a primary care physician, psychiatrist or psychologist, physical therapist, occupational therapist, and sometimes a disability case manager. This type of treatment provides the patients with the tools that they need to take control of their pain, as opposed to letting their pain control them.
The studies have come to the same conclusion: an interprofessional approach to pain management is 21 times more cost-effective compared to other methods. This reduction in cost can be attributed to a decreased need for pain medication, reduced calls for health care, and emergency room visits, and decreased disability payments. In the US, a country where 17.5% of gross domestic product gets spent on health care, it would only be logical to implement methods that help to reduce some of this financial burden, and that is why applying an interprofessional approach to pain management is the essential solution.
Negative emotions are like fuel thrown on the fire of pain, not only making chronic pain much worse, but even causing it to “roar” in some cases, says Beth Darnall, PhD, a pain psychologist and associate professor at Stanford University. Two-thirds of patients recently surveyed for the Arthritis Foundation’s Live Yes! INSIGHTS assessment said they felt depressed. And depressed people are three or four times more likely to develop chronic pain than others.
The reverse is also well-founded. Darnall says that positive emotions can significantly lower pain when patients stop focusing on how bad they feel. Many with chronic pain agree, noting that when they’re in a bad place emotionally, they’re less motivated to exercise and see friends and family. These are essential to changing pain patterns because they help break the pattern of thinking solely about pain, and they trigger the release of positive endorphins and the body’s natural opioids. When patients learn how expectations, beliefs and context all fit together, they know there is a pathway for them to gain more relief and control.
April Vallerand, PhD, a pain researcher and professor at Wayne State University in Detroit, says that a sense of powerlessness helps shape her patients’ perceptions of pain.
“If you perceive yourself to be disabled, you’re going to act like it,” she says. “Patients would say to me, ‘I’m fine as long as I don’t move from that recliner.’ Many were afraid to cook, drive, go to the mall. Well, that’s not life, that’s not function. My goal was to maintain or improve their function, despite chronic pain.”
The key is restoring their sense of control, which is known to reduce pain-related emotional distress and improve function. Vallerand designed a program for cancer patients she called Power Over Pain – Coaching (POP-C). POP-C delivered by trained nurses through phone calls and home visits. This establishes trust and helps caregivers understand patients’ backgrounds, stories and cultures, all essential for helping them learn to manage pain.
“We help people learn not to get so distressed, not to listen to their minds,” Vallerand says. “We are not trying to eliminate all pain. We are trying to reduce suffering, relieve distress and help people do more of the things they want and need to do in spite of pain. My question to patients is always, ‘What does this pain keep you from doing?’ If I can find out what that is, we can target that specific thing and work to get them back to functioning and doing the things that are important to them.”
She suggests nonpharmacological therapies like visualization, distraction and relaxation techniques as well as integrative treatments and spiritual resources. A couple of years ago, Vallerand and her colleagues, enrolling more than 200 cancer patients who are African American who research shows experience higher levels of cancer pain and less function than other groups in a randomized study. During the study, nurses visited and called the patients three times a week, working with them in POP-C’s three key areas. After five weeks, they reported significant improvements in pain, distress, function, and perceived control over pain. Patients who received home visits and phone calls but no coaching didn’t improve.
The U.S. once had hundreds of pain clinics, where people learned techniques to help manage chronic pain. When opioids came to the market in the 1990s, most of these clinics folded, but now there’s renewed interest in clinical pain programs. Two of the longest running are Mayo Clinic’s Pain Rehabilitation Center in Rochester, Minnesota, and Cleveland Clinic’s Chronic Pain Rehabilitation Program in Ohio. Both have long track records of success, and have helped patients live well without opioids, sleeping pills, anti-anxiety meds or acetaminophen (Tylenol).
“We address all the factors related to pain, so we work on physical conditioning, how people perform daily activities, and we also look at how people think and behave in pain and work on changing those aspects of their life as well,” she explains. “We see that pain starts taking over people’s lives over time. They start thinking about pain and ruminating about pain and worrying about the future. They behave in ways that inadvertently make things worse by avoiding activity and relationships that could be helpful, so we promote a very active rehabilitation approach.”
So is pain “all in your head”? NO! There are many factors to the very complex area of what we call pain! You might consider saving this blog for re-reading sometime in the future when you need it and feel better.
Joyce, this was a beauty, so well done, every detail, it’s as real as it feels, if it hurts it deserves attention and care, says I. Thanks for this lovely masterpiece! I will keep it close by. I’m so grateful for all ou and Sara do for all. Peace and Blessings to all, KD
Our body keeps the score of pain and trauma, for many years after suffering a massive stroke, I had the learn how to manage and embrace the pain.
We have to learn how to get beyond the suffering mentally and spiritually. Our bodies are our temples.
Excellent article.