The biopsychosocial model of pain, without the jargon.

What does 'biopsychosocial' mean?

The word is three words run together. Bio is the body: tissues, nerves, inflammation, sleep, fitness. Psycho is the mind: what a person believes about their pain, how they feel, where their attention goes. Social is everything around them: work, money, family, the claim, the culture they live in. The model says that pain, and illness generally, comes from the interaction of all three, and that no one of them explains the picture on its own.

George Engel, a psychiatrist at the University of Rochester, proposed the model in the journal Science in 1977. His target was the biomedical model that still dominates most people's picture of medicine: disease is a fault in the machinery, the doctor's job is to locate the fault and repair it, and whatever the patient feels or believes is noise. Engel's objection was that this left medicine unable to explain the most ordinary clinical fact of all, which is that people with the same findings fare very differently.

Pain medicine adopted the model more thoroughly than any other specialty, because chronic pain is where the biomedical model fails most visibly. Scans that look alarming in people with no pain, pain that persists after the tissue has healed, back surgery that fixes the disc and leaves the pain: none of this makes sense if pain is a simple readout of damage. A 2007 review in Psychological Bulletin by Gatchel and colleagues described the biopsychosocial approach as the most useful framework available for understanding and treating chronic pain, and summarized the evidence that treatment built on it outperforms single-discipline care.

In 2020 the International Association for the Study of Pain revised its formal definition of pain for the first time in four decades. The definition itself describes pain as an unpleasant sensory and emotional experience linked to actual or potential tissue damage, or resembling that experience. The accompanying notes make the model explicit: pain is always a personal experience shaped to varying degrees by biological, psychological, and social factors, and pain and nociception (the nerve signaling of damage) are different things that can occur without each other.

What does the biopsychosocial model NOT mean?

It does not mean the pain is imagined, exaggerated, or 'in your head' in the dismissive sense. This is the most common misreading, and it does real harm, because patients who hear 'psychosocial' often hear 'not believed'.

A few other misreadings are worth naming directly:

• It does not mean the scan was clean so the problem must be psychological. The model applies to every pain, including pain with obvious tissue damage. A fractured hip hurts more when the person is frightened and alone; that is the model working, not a sign the fracture is doubtful.
• It does not mean the patient is to blame. Fear of movement, low mood, and catastrophic thinking are responses to pain that have been studied for decades. They are learned, which is why they can be unlearned, and nobody chooses them.
• It does not mean the three parts are always equal. In the first days after an injury the biology dominates. Months later, when tissue has healed and the pain has not, the balance usually shifts. The model asks which factors are doing the work now, for this person.
• It does not mean the brain is the only source of pain. Nociception from tissue, nerve injury, inflammation, and disease are all real inputs, and they need proper medical assessment. The model adds to the biology; it does not replace it.

The distinction that makes all of this coherent is the one between nociception and pain. Nociception is the signaling of threat by nerves in the tissues. Pain is the experience the nervous system produces when it concludes the body needs protecting. The two usually travel together, which is why a stubbed toe hurts. But they can come apart in both directions: serious injuries sometimes go unnoticed in an emergency, and pain can persist, or appear, with no ongoing tissue signal at all. That second pattern is what the neuroplastic pain and central sensitization pages describe.

What are the three parts of the model, with concrete examples?

Each domain contains things that start pain and things that keep it going, and the second list matters more in chronic pain. The table sorts the most common examples.

What this looks like in one person

Consider a warehouse picker who strains his lower back lifting a pallet. Biologically there is a muscle and ligament injury that should settle within weeks, but he sleeps badly on the couch and stops walking. Psychologically, a colleague tells him about someone who ended up in a wheelchair from 'the same thing', and from then on every twinge is read as damage. He guards, he avoids bending, his back stiffens, which hurts more, which confirms the fear. Socially, his claim is contested, his supervisor stops calling, and his partner has taken on the school run and is tired of it. Six months in, the ligament has healed. The pain has not, and nothing about it is imaginary.

Notice that no single factor caused this outcome. Remove the colleague's story and the fear may never take hold. Settle the claim early and the limbo lifts. Keep him walking from week one and the deconditioning never starts. The three domains are one problem seen from three angles, and a plan that treats them as separate problems will keep missing it.

Why does treating one part at a time so often fall short?

Because the three domains are coupled, a gain in one is often cancelled by the other two. The usual sequence in chronic pain is a series of single-domain treatments, each sensible on its own, each undone by what it leaves untouched.

• An injection or procedure reduces the pain for a few weeks. The fear of movement and the lost fitness are unchanged, so activity does not increase, and the pain drifts back to where it was.
• Physical therapy prescribes graded exercise to someone who believes bending will cripple them. The exercises are under-dosed or skipped, and the therapist concludes the patient is unmotivated.
• Counselling helps with mood and fear, but nobody is working on movement, so the body stays deconditioned and the gains in confidence have nowhere to go.
• A return-to-work date is set while the claim is still contested and the supervisor is hostile. The person goes back, flares, and leaves again, now with evidence that work is dangerous.

There is also a structural problem. Each specialist sees one domain, and when the patient does not fit, they refer onward. The patient collects appointments, diagnoses, and imaging, often over years, with no one holding the whole picture. The research reviewed by Gatchel and colleagues points the same way: for people whose pain has become chronic, coordinated interdisciplinary programs tend to produce better results on function, mood, and return to work than the same treatments delivered one at a time. The chronic pain treatment guide walks through what that evidence covers.

Single treatments still have a place. A well-chosen injection can open a window in which movement becomes possible, and that window is worth having. The point is that each treatment works better inside a plan that knows what the other factors are doing, and that has someone responsible for the whole.

What does multidisciplinary pain care look like in practice?

One plan, several disciplines, shared goals, and progress measured in what the person can do rather than in pain scores alone. The ingredients vary by program, but most contain the same parts:

1. Medical review. Rule out red flags, confirm what the biology is and is not doing, and make sure any ongoing medical treatment is coordinated with the rest of the plan. Any change to medication stays with the prescriber.
2. Pain education. Explaining how a sensitized nervous system produces pain, so that a flare can be read as a sensation rather than as damage. Most of the rest depends on this.
3. Graded movement. Exposure to feared movements and activities in tolerable doses, expanding over weeks. This is the treatment for kinesiophobia, and it is where the biology and the psychology get worked on at the same time.
4. Psychological skills. Approaches such as cognitive behavioral therapy, acceptance and commitment therapy, and pain reprocessing therapy, aimed at the beliefs and reactions that keep the alarm on.
5. Sleep, pacing, and daily structure. Often the fastest lever on the biological side.
6. Work and social planning. Contact with the employer, a realistic return-to-work pathway, and attention to the claim, the finances, and the people at home.

Traditional interdisciplinary programs deliver this in a clinic, often full-time for several weeks, with a physician, physical therapist, psychologist, and case coordinator in the same building. They work, and they are scarce. Many regions have none, waiting lists are long, and few people can leave work and family for a month. Home-based and virtual programs exist to deliver the same combination without the building.

Karuna is one of those programs, and it is founded on the biopsychosocial model. A clinician reviews each case before the program starts and provides oversight throughout, covering the biological side and confirming the fit. Short daily VR embodiment exercises on a provided headset work on the body map and on fear of movement at the same time. A weekly one-on-one session with a dedicated pain coach covers beliefs, flares, sleep, work, and the parts of life pain has been running. The 12 weeks happen at home. The full structure, and the outcome data Karuna has collected along with its limits, are on the how it works page. Karuna takes workers' compensation referrals, and the care team confirms coverage case by case.

What this means for you

If you have chronic pain

When a clinician mentions psychological or social factors, they are using the standard way pain is understood, and they are usually looking for the factors that can still be changed. Your pain being real was never in question. Useful questions to ask: which of the three domains do you think is doing most of the work in my case, what are we doing about each of them, and who is coordinating the plan. If the honest answer to the last one is nobody, that is the first problem to fix.

It also means that progress in your beliefs, sleep, fear, and activity counts as progress, even on days when the pain score has not moved. In most recoveries from chronic pain, function and confidence improve before pain does. The living with chronic pain guide covers what that looks like day to day.

If you are a clinician

The model is only useful if all three domains are assessed, and the psychological and social ones are the ones most often skipped. Brief screens for fear-avoidance and catastrophizing, such as the TSK, the FABQ, and the Pain Catastrophizing Scale, take minutes and often predict the course better than the physical findings. Ask about the claim, the employer, and who is at home. Language is treatment too: 'degeneration', 'wear and tear', and 'the worst spine I have seen this week' are inputs to the patient's pain system, and they will still be there in a year.

If you are a case manager or adjuster

The social domain is frequently the one you have the most control over. Claim delays, contested treatment, silence from the employer, and the absence of modified duty each keep the loop running, and none of them show up on a scan. Function and return to work are the outcomes that track with the model; pain scores alone will mislead. The evidence on interdisciplinary care argues for bringing it in once pain has persisted for a few months, rather than holding it in reserve as the last option after everything single-domain has been tried.