Can you train pain?
Can you train yourself to find things more or less painful?
Cambridge University neuroscientist Duncan Astle got stuck into Ali's question...
Duncan - It's an interesting question from a kind of basic science perspective, but also from a clinical perspective. One of the big challenges in medicine is trying to manage people's pain. It's very difficult because ultimately there's no way of knowing how much pain the participant or a subject or a patient in the hospital is in.
And so it's very hard to know how much medication they should be given. So there's lots of variability in how sensitive different people are to pain. And one of the big sources of variability is genetic. So the way that this is studied in the lab is they will use something like a heat sensor or a cold presser to create a kind of painful sensation. And we know that variability in heat pain sensitivity, about 26 to 32 percent of that can be attributed to underlying genetic differences, but it's as much as 60 percent for variability in cold presser pain.
Chris - And what are those genes actually doing, to make say you feel a lot more pain for the same stimulus than the me?
Duncan - Those genes could be doing various different things. So there there's a kind of a long pipeline going from the affector - when you receive the sensation of the pain - that travels up to the chord then all the way to the brain and then back out again. And there are multiple steps at which for instance those genes could be coding for different types of receptor, that could be coding for different types of transmitter, or they could be involved in higher level neurobiological systems.
So one source of variability that we know about is that there are areas of the cortex, the outer layer of the brain that's usually we think of as being responsible for the higher order cognitive skills. So areas of the frontal lobe like the insula which is kind of just behind your eyes and also somatosensory cortex, we know that variability in the extent to which people can up-regulate those areas seems to be involved in their ability to regulate pain.
Chris - So it's a bit like high then, in the sense that there are loads and loads of genes that probably determine how tall you get. But it's not gonna be down to one gene alone.
Duncan - Exactly. So the way that we work out these percentages one way that they do is with twin studies. So if you get identical twins and not identical twins, then you know roughly speaking how much shared genetic material those participants have. And from that you can calculate what proportion of the variability is genetic.
But of course it doesn't which genes it is or how many genes it is. There are different types of pain sensation and they seem to have different types of genetic susceptibility. And that implies that there are underlying the system physiologically distinct different pain systems. Some of them might be more genetic than others. And so for instance gender is an important predictor of pain. So people who are male have slightly higher pain tolerances than female. It's about 8 percent for heat pain but much larger for cold presser pain.
The fact that variability in the extent to which you can up-regulate these higher order almost cognitive areas of the brain, the fact that that will modulate your pain sensation, implies that it is to some degree trainable. And we know that there are all sorts of different interventions like practicing meditation for example. And people who are experts in meditating do claim that it helps them to moderate their experience of pain. And so for instance there are people who practice different types of meditation prior to childbirth.