A man jumps from a height on a construction site. He lands on a nail that goes right through the thick sole of his shoe. Screaming with pain, he is carted off to hospital. Once there, it appears that the nail went straight between two toes. There is nothing wrong with his foot.
A typical example of the brain making a little error, says Kai Karos, researcher at Experimental Health Psychology. “Acute pain is a warning to our brain that our body is being threatened. The brain then tries to predict how great the threat is. Previous experiences play a role here, but also what you see and hear. That man saw the nail go through his shoe and thought he had a serious injury. On the other hand, someone who is severely injured – for example, a soldier who loses his arm in battle – feels hardly any pain at all, because at that moment he is still full of adrenaline.”
Another example: “A study has been carried out in which people have a stick, cooled down to -20 degrees, pressed to their necks. At that temperature, you no longer feel the difference between hot and cold. Sometimes the stick is red, sometimes it's blue. The people who had a red stick, reported that they had more pain than the test subjects with a blue stick. We find heat more threatening than cold, we associate red with heat and danger.” In this instance, the visual stimulus gives the brain the wrong information. The same experience – a stick of -20 degrees held to your neck – therefore feels different in the two cases.
Chronic pain – which continues for more than three months – may also be a mistake made by the brain. “That is what we think at the moment. The brain registers a threat that is no longer present or never existed. It doesn't make the pain any less real.” Still, there are doctors who feel that if there is nothing wrong with the body, the pain can't be real either. “They can't help the patient any further or even think that the patient is feigning. That is very frustrating for such patients,” says Karos.
These days, patients with chronic pain are increasingly given behavioural therapy. “In doing so, you influence the thoughts they have regarding pain, so that they can deal with it better. The more afraid people are of pain, the more intense their experience is. For example, they will start to avoid certain movements, because they were painful in the past. Because of this, they won't be able to do certain activities and so they start to limit themselves. You also see that they catastrophise pain. When they feel something, they immediately think that it is something serious, that it will never get better. The aim of the therapy is to expose them to activities that they are afraid of, to show them that nothing serious will happen.”
Karos himself is carrying out research into the social factors: to what extent do people’s surroundings influence the amount of pain that they experience. “Test subjects receive electric stimuli, but beforehand a fake test subject determines the level of stimuli they receive. They always choose 10, but we let the one group choose between 1 and 10 and the other group between 10 and 20. Some test subjects therefore think that the other person wants to hurt them as much as possible, the other that they will be given as little pain as possible. Even though everyone receives the same level of stimuli, the group that thinks someone is out to hurt them experiences more pain. The experience is influenced by the social surroundings.”
Chronic pain patients also have to deal with that. “They feel that people judge them negatively because they are not active in society. Or people in their surroundings tell them that they are making too much of it. The consequences are that they are shut out and become isolated. This leads to feelings of depression, which in turn makes the pain worse. That is why it is a good thing that more attention is paid to not only the physical aspect but also the psychological and social factors.