But RSI has a clear physical mechanism. I don't know as much about chronic back pain, but considering how much physical stuff there is in our back, I'd assume it's similar.
Or does "physical mechanism" mean something other than it seems to mean?
He was also clear that this is not always the case, and that direct physical causes should be looked for by a specialist before pursuing psychological remedies.
The idea is the pain is very, very real, and very, very painful. But that the cause is psychological.
The reason why RSI and back pain type issues persist is because psychologically they are very easy to justify. Of course we put load on our backs! Of course we do repetitive things! So it's easy to draw the conclusion that this is the cause, especially for your brain. This prevents people from exploring a root cause.
It's interesting material, but I think you have to be pretty open minded to consider it.
Imagine that RSI is not caused by bad posture, lack of exercise, and repetitive motions alone. For example, there are many people with bad posture, who don't exercise, who use repetitive motions and do not have RSI (me, for example ;-) ). Imagine that in addition to these things a required trait is that the muscles are slightly tensed. Imagine that the tense muscles constrict blood flow. This causes an inflamation in the area and with repetitive motion (or even lack of motion) it generates an injury in the area.
Imagine that when you believe that you have solved the problem (by using a special keyboard, or changing the way you sit or changing the way you move) that your muscles relax just that little bit. Now the blood flows freely, there is no inflamation and the RSI goes away. You think it's due to your physical actions, but in reality you are cured only because you believe that what you did worked.
The idea behind the book (as far as I can tell -- I decided not to read it) is that conditions like RSI are real. The physical cause is real. However, the conditions necessary to cause the condition to occur are mental. It's a fairly compelling idea. RSI is a similar situation to the back pain that the author of the book studied. Many people suffer from it and the cure seems to differ widely -- if you can be cured at all. May of the cures don't really have convincing experimental evidence to show that it actually relieves any physical problems. The efficacy is based only on the apparent lack of new symptoms.
Now, I'm of two minds with this book. On the one had, like I said, the idea is compelling. The author believed that most chronic back pain's underlying cause was mental. The physical issues that in turn caused the pain, were in turn caused by the mental issue. The author apparently had considerable success in his practice, but I think it is important to note that his practice was for helping people who had back pain where no conventional treatment helped. So he's working from a point of sampling bias. While he may be correct that this occurs, it is hard to get an idea on how frequently it occurs.
This is different from the general effects of stress, and different from purely physical factors.
Speaking for myself, I don’t have serious back pain, but when I occasionally experience momentary strong anxiety my back muscles get noticeably tight/strained, especially while sleep deprived. Drinking 1 beer typically alleviates that, or I’m sure some other anxiolytic medicine could.
I would not be surprised at all if chronic severe anxiety (e.g. taking care of a chronically ill child, working a high-stakes short-deadlines job, living with an emotionally abusive person, experiencing trauma and then suffering PTSD, ...) might cause me to develop a real back pain problem.
My experience with most serious medical things is that doctors have a clear general-audience explanation, because part of their job is making patients feel like they understand what's going on. But if you get into the details, the good doctors will say, "Well, actually, the picture is much murkier, but here's what we know based on studies X, Y, and Z, but there's a lot yet to learn."
Back pain in particular is an area of open dispute. Many people have many theories, all of them very hard to test. When I was dealing with back pain, a spine-center doctor recommended a book called "Treat Your Own Back" [1]. It was hugely helpful to me. And in it, the doctor explains that he hit upon his method because a patient came in, used a piece of equipment that was set up totally the wrong way, and said, "Gosh, doc, that was great!" It led him to reexamine what he had been taught about backs, coming up with a different "clear physical mechanism" to explain a common class of pain.
That we are still figuring something out does not mean it's psychosomatic. It doesn't mean it's not, but a doctor suggesting otherwise is doing the medical equivalent of "god of the gaps" theology, where anything mysterious is attributed to your preferred cause.
[1] https://www.amazon.com/Treat-Your-Back-Robin-McKenzie/dp/095...
Are there physiological differences between people that explain this? Probably. But I suspect in many cases Sarno is right, it’s not purely physical. Look into neuromatrix theory and non-proprioceptive pain for a somewhat more scientific attempt at an explanation.