The Evolution of Pain Theory

According to the biopsychosocial pain theory, we all experience pain differently to a wide variety of reasons

What is pain? Traditionally, doctors thought that pain meant something was injured or damaged in the body. But pain theory is evolving. For example, how can damaged tissues cause pain in a phantom limb, when there is no limb to be damaged?

To explore the evolution of pain theory, we first have to know what the theory used to be.

Pain Theory Of Times Past

Specificity Theory

First proposed by Von Frey, Specificity Theory posits that the brain has specific transmitters for pain. What exactly does this mean?

Von Frey believed that the pain system was separate like sight and hearing are separate senses. In this theory, the pain system is designed to only sense painful sensations.

Strong’s Theory

Strong has a different idea, however. He believed that the sensations associated with pain (heat or cold) were real, but psychological displeasure makes those sensations painful.

To describe it more bluntly, our pain is dependent on our brain’s say-so. Therefore, it was only when humans evolved a conscience that we began to feel pain.

Pattern Theory

In Pattern Theory, J.P. Nafe disregarded the concept of a separate pain system. Instead, he believed that the same neurons that transmitted the sensation of a caress were responsible for transmitting the pain of a slap.

What sets Nafe’s theory apart, is his idea that different neuron signaling patterns determine if a sensation is painful.

Central Summation Theory

Livingstone, on the other hand, believed that pain was caused by tissue damage. Tissue damage activates the neurons that transmit pain, and the more damage there is, the greater the pain.

Livingstone’s theory is very similar to the traditional pain theory described in the introduction. It is based on concrete evidence of damage, and pain is the body’s reaction to being damaged.

Traditional pain theory suggests that damaged tissues send messages to the brain through the nervous system
Photo by Camilo Jimenez

Biopsychosocial Model of Pain

In the biopsychosocial model of pain, scientists believe that the biological response is impacted by social and psychological conditions. Our perception of pain is influenced by our mental state, our social lives, and our physical sensations.

How Is The Biopsychosocial Pain Theory Different?

Scientists and researchers developed the above pain theories over a span of nearly two centuries. There are pain theories that I didn’t even include in the list!

Thus, we have to ask ourselves, “what makes the biopsychosocial model different?”

Biologists study the makeup of bodies, whether animals or plants. Often, when biologists study humans, they focus only on the physical body and reactions they can see. All of the above theories recognize the importance of the body and its reactions.

Some theorists even recognize the importance of the psychological response, as seen in Strong’s theory!

For example, when I was younger, my brother kicked a soccer ball and hurt his toe. While his shoe was on, he was fine. But, when he took his shoe off and saw the blood, he reacted much more strongly. It was as though his pain increased.

Why? Because when our body sees blood where it shouldn’t be, we know that something must be wrong!

Moreover, some people react more strongly to pain than others. Despite having the same sprained ankle, some people will walk around fine, and others will struggle to put weight on their ankle for a week. The psychological response is different.

Ultimately, what really sets the biopsychosocial model apart is the inclusion of social factors.

Who taught you how to respond to pain? Did your parents “laugh off” a minor injury, or were they hyper-worried? Were injuries taken seriously in your classroom, or did the teacher not have time for your concerns? Were you raised in a culture that acknowledges pain, or was the focus on function and healing?

This pain theory recognizes the importance of many factors, especially the factors outside of the human body! And that is what makes this theory unique (especially in the eyes of an anthropologist).

Applying Pain Theory To Pain

So how does our theory about pain change the way we treat it?

Firstly, much like wellness and overall health, all pain requires an individualized approach.

Some people don’t want painkillers, and others need them much more. Other times, mental illnesses, like depression or anxiety, can increase the sensation of pain. If a patient’s family does not support their recovery at home, their social environment may be a hindrance to their healing.

When we can see what’s causing the pain (bones, blood, or barf) it is easier to understand it. It is easier to treat obvious pain, like a twisted ankle, a nasty scrape, or a stomach bug.

However, in Canada, an estimated 7.63 million Canadians aged 15 or older live with chronic pain. If we are looking for damaged tissue or a “reason” for the pain, we may not find it. That does NOT make the pain any less real.

That is a LOT of people who cannot be treated by traditional pain theories.

Pain Theory and Migraines

The biopsychosocial pain theory allows me to interrupt my migraines in a more holistic and mindful way
Photo by Aaron Blanco Tejedor

I suffer from chronic migraines.

It is rare that I make it through a whole week without a migraine that requires medication to control. When I experience a migraine, it usually starts on one side of the base of my skull. Without medication, the migraine spreads through the entire side of my face and jaw.

I do not have migraines nearly as bad as some people. I barely experience an aura, and my vision doesn’t suffer.

According to traditional pain theories, my migraine signifies that something is wrong or damaged in my brain. And it FEELS like there is something wrong in my brain. Migraines helped me understand why the Incans practiced trephination.

However, according to the biopsychosocial model, my migraine pain is caused by several factors:

  1. Biology: I am biologically predisposed to migraines and/or susceptible to specific migraine triggers
  2. Psychology: my migraines are more severe when I am stressed or my mental health is suffering
  3. Social: who I am with, where I am, and how I react socially are all factors that can aggravate my migraines

Moreover, according to this theory, I can treat my migraines with more than just medication and watching my migraine triggers!

I use mindfulness and meditation to cope with the migraine pain until I can take my medications. I also use meditation and other self-care practices to alleviate the stress that contributes to my migraines.

Pain Theory Beyond Migraines

How does my personal experience with migraines relate to other sorts of pain?

According to the biopsychosocial model of pain, we can change our pain by changing the factors around us as well as how we perceive pain.

For example, a positive mindset makes a huge difference when it comes to managing pain.

Moreover, the more we understand our pain, the less painful it becomes. That is why it is important to speak to your doctor about your pain and its potential causes. If you do have an injury or tissue damage, ignoring the pain might make it worse. On the other hand, if there does not seem to be a concrete biological cause to your pain, you can change other factors in your life!

Disclaimer: above all, pain is a message from your body. Unfortunately, doctors do sometimes miss symptoms or dismiss valid concerns on occasion. If you are not comfortable with your doctor’s conclusion, seek a second opinion from someone who is specialized in the area you are concerned about.

Hurt vs Harm

Another important aspect of this new and improved pain theory is understanding the difference between hurt and harm.

Your pain is real. If walking hurts, it hurts. If your neck is sore, your neck is sore.

But, you are not necessarily harming yourself by walking on a sore foot.

Pain theory suggests that retraining your body to manage pain is essential
Photo by Ryan Snaadt

This concept is especially important if you are pursuing physiotherapy for your pain. Oftentimes, physiotherapists will push a client, in order to improve pain tolerance and function. A licensed physiotherapist is trained how to properly execute therapeutic exercises, and prevent further injury.

When you can push through the pain, you can increase your day to day function, and learn to manage pain better.

So what is the difference between hurt and harm?

Pain hurts. That’s kind of its schtick. However, while we are taught that pain means to stop – that it signifies damage – that is not always the case. Sometimes, your body is sensitized to pain, and it overreacts to different sensations as some immune systems overreact to a peanut.

It is getting past this sensitization that allows us to live our lives.

Stretching a sore muscle after an intense workout, is a great example of how sometimes we hurt, but that hurt does not translate into harm.

So What Is Pain?

Pain is a very real sensation. When our neurons send signals to our brain, it is our brain interprets these signals as pain. Sometimes, the brain interprets non-damaging or safe signals as pain, especially when our bodies become sensitized to various triggers.

If you are in pain, it is important to speak to your doctor, to ensure that you are not injured or sick. However, if there is no physical source for the pain, it can be possible to manage these sensations with other strategies.

Why? Because our pain is influenced by more than our neurons and tissues. Our mental state can influence how we feel pain. The way we are taught to react to pain can impact how painful an injury seems. There are biological triggers for pain, but we cannot forget the role that psychological and social environments play when our brain is interpreting neuron signals.

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