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Chronic pain has a purpose: hypervigilance against predation (at least)

 •  • by Paul Ingraham
Weekly nuggets of pain science news and insight, usually 100-300 words, with the occasional longer post. The blog is the “director’s commentary” on the core content of a library of major articles and books about common painful problems and popular treatments. See the blog archives or updates for the whole site.

In late 2019 I wrote an article asking the question, “What if chronic pain is a feature, not a bug?” It was based on some high-falutin’ speculation that otherwise puzzling chronic pain might actually be just as essential to our survival as acute pain, just over longer time-scales.

More than a year later, I stumbled across this tweet from pain researcher Jeffrey Mogil:

We’ve always been taught that “chronic pain has no purpose; it’s a pathology.” As Robyn Crook et al. showed in squid, and we now show in mice, this isn’t true. The purpose is to produce hypervigilance against predation. Likely true in people too (minus the predation part!)

Those papers report decent empirical evidence of almost exactly the same point I was making (I didn’t talk about predation at all though). So I am not so far out on a lonely speculative limb as I was, which is nice. Physiotherapist Derek Griffin summarizes:

Pain is such a powerful motivator. It captures our attention, makes it difficult to focus on other things. Yet appears to be advantageous in an evolutionary sense to aid survival. Hence why it isn’t so easy to just “accept” pain. When it is “designed” to produce vigilance.

There are some good, thoughtful responses to that tweet, worth a look.

And still more synergy on this theme. At the 2021 Oregon Pain Summit, Dr. Melissa “Missy” Cheyney spoke about the “smoke detector” theory of pain. Smoke detectors are a better-safe-than-sorry alarm system, and probably the pain system is too. A hair-trigger and a lot of noise basically guarantees false alarms, but also that we will never fail to notice or react to dangerous stimuli. Dr. Cheyney: “The cost of more pain is often less than the cost of too little pain.” And Jeffery Mogil again: “Evolution only cares about survival (and procreation). If you’re miserable but still alive, evolution prefers that to happy and dead.”

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