Why do we compulsively pick scabs?

06 August 2008

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Picking scabs. We all do it, and funnily enough, we all squirm when we think about it...  

I’m actually cringing as a write this. We’ve all had that little, tiny pimple on the tip of our nose. No one could even see it. But maybe, we’re a little stressed, a little bored, so we started to scratch, and scratch, until… we have a scab, and then we keep on scratching, until it’s nice and smooth. That little tiny pimple is now red and inflamed, and everyone can see it. We knew it would happen, even while we were doing it, but we just couldn’t help ourselves. So we kept on scratching. Why? Why do we do it to ourselves, time and time again? Because, just like biting our nails, and checking our mobiles for an SMS when we know there is nothing there - it’s a habit that we can’t break.

We get habits by doing something enough times that the neurons in our brain build a highway to quickly get us from one trigger point to performing the habit. I used to always eat in the ad breaks of TV shows when I got home from school. Now, as time has gone on, as soon as an ad comes on the television, I automatically get up and go to the fridge, often having to stop myself to say – I’m not even hungry (but mostly I just think, since I’m at the fridge, I may as well eat.) So the first few times, my neurons had to find there way around my brain. The ad came on TV, and I actively thought, time to go to the fridge. After weeks, maybe years, of coming home from school and eating my afternoon snack in front of Family Feud the neurons knew exactly what to do. The highway was built: ad comes on, fridge. The fact that our brains can “re-wire” like this, is called plasticity. It also explains how we learn, remember and develop new skills.

The reason kids learn much faster than adults is because the younger we are the more plastic, and mouldable our brains are. But, research is showing that the old adage that “You can’t teach an old dog new tricks” isn’t all true, and the adult brain is still plastic, it just might take longer to learn new skills, and develop new habits. Unfortunately, the less familiar adage, “You can’t teach a stubborn and cranky old dog new tricks”, is actually quite true.

Habitual behaviours can take days or years to develop, depending on the complexity of the habit, and how often you do it, but science is showing, that once you’re neurons have built a habit highway, it stays remarkably fixed and difficult to break. The ease that the nerves get triggered and start driving down the road means that our habits are often performed automatically, and unconsciously. This allows our attention to be focused elsewhere, which can be a good thing - we can drive home while chatting to a friend. But it can also lead us to go to the fridge when we’re not hungry, or pick a scab when we know we shouldn’t, without even realising what we’re doing.

Compulsive Skin Picking is called dermatillomania, which sounds more like a funky 80’s band to me, but in some cases it’s quite serious and can lead to infections, bleeding and permanent scars. Like a lot of repetitive habits–including hair pulling, and nail biting - scientists aren’t sure why we do it, but they know that the same parts of the brain keep lighting up.

Research has shown that often before we start picking our skin, or pulling our hair, we are usually in a state of stress, but doing something fairly sedentary, like sitting in front of a computer. The mix of high stress and sitting still seems to affect the release dopamine throughout the brain, which is a chemical that increases desire and motivates people to seek positive rewards. These rewards include food, sex, and that secret sense of satisfaction that we get when we have picked that scab, or bitten a nail. For some fairly bizarre reason, picking scabs and biting nails is also thought to release endorphins through our bodies. And in some animal models, it’s been shown that animals that excessively pull their hairs have more receptors in their brain to take up endorphins. If this is true for humans, people who are particularly compulsive about their repetitive habits may have more endorphin receptors in their brain as well. This means that they will get more enjoyment out of picking their scabs than others, and dopamine, which controls our need to seek positive rewards, would be released in higher doses.

New studies are showing that dopamine has an important role in re-moulding our brains, and building that habit highway. Dopamine, while increasing the plasticity in our brain, also controls how excitable our neurons are - so not only does dopamine make our brains ripe for re-wiring, it sends out the construction workers to build the road, so before we know it – we’ve got ourselves an unconscious habit.

But we aren’t slaves to dopamine. There are other chemicals in the brain, like serotonin, that allow us to stop doing whatever it is that we’re doing. I don’t have to grab food when I’m at the fridge, and I can stop picking that scab if I consciously focus on it. And it’s this focus that seems to be the key to breaking habits. It’s convincing yourself that there is no reward at the end, no enjoyment from picking that scab. It’s focusing your attention elsewhere, and when you’re feeling stressed and deskbound getting up, and moving around… just making sure you avoid the fridge.

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