The Role of the Immune System in Pain Perception: Why "Psychogenic Pain" Is an Outdated Concept

Photo by Adrian Swancar on Unsplash.

Ever been told that “it’s all in your head” when there’s been no obvious cause to your chronic pain? Perhaps you’ve been referred to a psychologist or psychiatrist when bloodwork and scans don’t reveal anything? Maybe you’ve simply been told that you’re making it all up to get attention?

If you’ve been gaslit in any of these ways, you’re not alone - especially if you’re a woman. While one in five Australians over the age of 45 are reported to experience chronic pain, 40% of women in Australia report chronic pain. This is twice the national average over 45.

What’s more, one in three women with chronic pain report having experienced “insensitive and disrespectful” practitioners.

I experienced this kind of gaslighting when the symptoms I reported to a GP were fobbed off in 2020. Within a week, I had diagnosed my own condition by ordering the same tests privately that he refused to order through the public health system. I then took these results to another GP, who confirmed the diagnosis.

Why are so many of us struggling to get answers when we have chronic pain? And what can we do to reduce chronic pain?

The Immune System and Pain

Pain isn’t just a sensory signal that gets sent from your body to your brain. It’s a multifaceted experience that involves the nervous system, immune system, and brain. The immune system plays a crucial role in pain perception, especially when it comes to chronic pain.

At the core of this process is inflammation. In response to injury or infection, the immune system activates and releases various substances, such as cytokines, prostaglandins, and histamines, that trigger inflammation. This inflammation can increase the sensitivity of nerve endings, making them more responsive to stimuli. As a result, even a small amount of pressure or a mild sensation can feel painful.

There’s an advantage to this increased sensitivity in acute contexts. Pain acts as a signal, helping to modulate behaviour to prevent you from partaking in whatever is causing the pain. It’s meant to be a short-term measure that allows you to avoid further organ and tissue damage whilst healing from whatever’s happened.

The problem is when inflammation lingers. In the case of chronic pain, inflammation becomes persistent. The immune system may remain activated long after an injury or illness has healed, causing ongoing pain. This is often seen in conditions like arthritis, fibromyalgia, and chronic back pain, where inflammation and immune dysfunction are at the root of persistent pain.

There’s also a phenomenon known as central sensitisation, where the nervous system becomes more sensitive to pain signals over time. In chronic pain conditions, the immune system’s inflammatory signals can affect the central nervous system (CNS), making it more responsive to pain. You experience neuroinflammation in the brain and/or spinal cord, which can then drive inflammatory processes in the periphery. This is why pain perception can persist even in the absence of an ongoing injury. Essentially, both your nervous and immune systems are contributing to the process of amplifying the pain experience.

Why "Psychogenic Pain" Is an Outdated Term

For decades, people suffering from chronic pain were often labelled with the term "psychogenic pain", which implied that the pain had no physical cause and was instead rooted in emotional or psychological issues. This term was commonly used for conditions like fibromyalgia, chronic fatigue syndrome, and irritable bowel syndrome, despite evidence that these conditions involve real physiological changes, including immune system dysfunction, inflammation, and altered pain processing.

I was shocked when a unit I had to complete as part of my Master of Counselling covered the concept of psychogenic pain as though it was still relevant. It placed firm emphasis on the role that the brain plays in chronic pain and pain perception, with ZERO acknowledgement of the role of the immune system in chronic pain.

As far as I’m concerned, the labe “psychogenic pain”l is outdated because it ignores the complex, multifactorial nature of pain. It oversimplifies the pain experience and wrongly places the blame solely on psychological factors, which can further isolate individuals and contribute to stigma. More recent research has shown that psychological distress, such as stress or trauma, can certainly exacerbate pain, but it’s never the sole cause.

In fact, pain perception is not limited to what’s happening in the brain. While emotions can influence how pain is felt and how the brain interprets it, the idea that pain is purely psychological has been debunked. Rather than being "all in your head," pain involves intricate biological processes that are both real and measurable.

The problem is that most health practitioners aren’t taught how exactly these biological processes are linked, nor how they can affect the overall balance of inflammation (and therefore pain) that you're experiencing.

The Biological Mechanisms Behind Chronic Pain

Chronic pain can result from dysregulation in the immune system, which can activate pain pathways long after an injury has healed. This can involve:

1. Chronic Inflammation
   Persistent inflammation can overwhelm the body's ability to resolve it, leading to ongoing pain. An example of this would be mast cell activation syndrome (MCAS), where somatic gene mutations in immune cells result in an ongoing inflammatory response. Inflammatory molecules like cytokines and prostaglandins can sensitise nerve endings, causing an exaggerated pain response.

2. Neuroinflammation
   The activation of the immune system in the brain (neuroinflammation) has been linked to conditions such as chronic pain, depression, and anxiety. When this inflammation becomes chronic, it can alter the way the brain processes pain signals, further amplifying the experience of pain. The brain and body create a reciprocal feedback loop, where each contributes to an inflammatory storm that can leave you with an outsized response to whatever the original stressor was. This doesn’t mean you’re making it up or overreacting, though - the underlying cause still needs to be treated.

3. Peripheral Sensitisation
   When the immune system is constantly activated in response to an injury or infection, it can lead to increased sensitivity in the peripheral nervous system. This heightened sensitivity makes individuals more vulnerable to pain. Again, this doesn’t mean you’re overreacting. Being more sensitive to pain can be a beneficial adaptation under the right conditions. It’s also a sign that something is triggering a pain reaction ongoing.

Pain Isn't "All in Your Head"—But Emotional Stress Relief Still Helps

It’s critical to emphasise that pain isn’t simply a mental phenomenon. While it’s true that emotional and psychological stress can influence how pain is experienced, it’s important to recognise that there is real, measurable biology behind pain that can be affected by the immune system, nervous system, and inflammation.

However, this doesn’t mean that emotional stress relief isn’t beneficial for managing pain. On the contrary, as I can attest from personal experience, stress—whether physical, emotional, or environmental—can exacerbate pain by triggering inflammation and immune system activation. By reducing stress through techniques like mindfulness, breathing exercises, yoga, or engaging in enjoyable activities, individuals can help regulate the nervous system and reduce the overall inflammatory load on the body.

I want to highlight something else here as well, though: if stress or trauma is contributing to your chronic pain issues, then your pain still isn’t “all in your head”. It’s having an impact on your entire body. And the pain that you’re experiencing is still a signal meant to change your behaviour and prevent long-term damage.

Working on processing past events and making meaningful changes (if appropriate) to your beliefs and outlook on life can be helpful, but you may still need to address the physical impacts of stress. Both need your attention.

Practical Tips for Pain Management

1. Upregulate Pathways that Resolve Inflammation
   Pro-resolving mediators (PRMs) are compounds that we can either ingest or make ourselves that help resolve inflammation. They won’t actually resolve the cause of inflammation if it’s a chronic issue, so please keep that in mind, but they can help with managing symptoms and promoting tissue repair. They’re derived from omega-3 and omega-6 fatty acids and are produced through enzymatic processes, mostly in the liver. In supplement form, they’re derived from sources like herring roe but if you find they’re beyond your budget (they’re quite expensive) or prefer a plant-based alternative, turmeric can stimulate your body’s production of PRMs. Just make sure that your diet has plenty of omega-3s and some omega-6 fatty acids in it to provide the substrates for PRM synthesis.

2. Get Adequate Sleep
   I can’t stress enough how important getting good sleep is to resolving inflammation. Sleep is the one time of day when our bodies are able to properly undertake clean-up processes that stimulate inflammation resolution. I’m sure you don’t need me to tell you this, but making sure that you wind down properly at night, keep your sleeping environment cool, and make sure to block out anything that might interrupt your sleep (for parents and caregivers, within reason) can make a huge difference. The other tip that I love and have found really useful for getting better sleep is to stop waking up with an alarm. I get that there might be practical issues with this for some, but if you don’t have a legitimate reason for waking up with an alarm, then it’s worth giving it a try.

3. Get Moving

   I know this can be one of the least appealing pieces of advice to hear when you’re in chronic pain, but getting your body moving can be really helpful when it comes to dealing with chronic pain. The reason why? It promotes blood flow, which can improve nutrient delivery and therefore healing to inflamed areas. In saying that, you don’t want to create more inflammation than you’re resolving, so choosing gentle movement that doesn’t cause you to feel too fatigued or more pain is the way to go. Choose based on your own window of tolerance. Even just stretching or walking can help.

4. Use Mind-Body Practices to Calm Your Nervous System

   I always used to be one of those people who struggled with meditation, yoga, or breathwork. And to be honest, I still am. I like things that happen quickly. But when I began using HeartMath, I experienced relief from my symptoms almost immediately, more than any supplement or dietary change I’d tried at that point. These days, I still practice HeartMath or if I’m not in the mood for it, I’ll use simple breathing techniques while being guided by my favourite free app called “Awesome Breathing”. Even just two minutes a day of either of these can be beneficial.

5. Mindset and Pain Acceptance
   One of the most empowering things for me when I was on my journey with chronic pain was understanding that it was real. I still experienced pain and fatigue much of the time, but it was a lot easier for me to maintain a positive mindset when I knew that it had a biochemical underpinning. It felt a lot more controllable then because it was no longer mysterious and inexplicable. I knew there were things I could do to manage and improve my symptoms.

Pain Is Real—And It’s Not Just In Your Head

The final thing I want to talk about here is why you may not be getting the answers or treatment you need. If you’re biologically female, it’s almost ridiculously easy to explain: Western medicine has a long history of labelling women as “hysterical” or hypochondriacs. Apparently, we don’t even know our own bodies well enough to decide when there is or isn’t something wrong worth further investigation. Medicine is downright misogynistic, and there’s plenty of evidence that that misogyny is ongoing.

The other reason is that the brain and body are often treated as separate entities. There’s a long history here as well, but perhaps the most significant perpetrator of this myth is Descartes. Often considered the father of modern medicine, he proposed the notion of mind-body separation (known as dualism) in the 17th century. Our entire Western medical model is now based on this idea. In fact, I would argue that it has taken the reductionist principles that Descartes founded Dualism upon to new heights with the introduction of ever-more medical specialists.

My mind boggles at the thought that researchers have boiled most, if not all, non-heritable chronic diseases down to one thing (mitochondrial dysfunction), yet very few practitioners treat mitochondrial function. We’ve managed to separate all of mitochondrial dysfunction’s symptoms into different branches and specialty areas of medicine without actually treating the issue itself.

I hope that, someday soon, there’s a shift in how we view health and disease states and begin to see people as a whole person, not just a set of organs and tissues acting up for no apparent reason and separate from one another. Maybe it’s naive of me, but hey, I’m an optimist.