Hypnotism produces physical changes in the brain, according to a study showing that the favourite stage act of 19th- century magicians has a genuine scientific basis and could play an important role as a painkiller in medicine.
Scientists who hypnotised a group of volunteers have shown that the state induces a change in blood flow to the brain that cannot be explained by the power of suggestion. Hypnotism, they concluded, is for real.
The research by scientists from the universities of Harvard and Stanford has demonstrated beyond doubt that some people are highly susceptible to hypnosis and that when they are hypnotised they use their brain subconsciously in a way not previously thought possible.
David Spiegel, professor of psychiatry and behavioural sciences at Stanford's school of medicine, said clinical trials showed that hypnotised people, especially children, could cope more easily with extreme pain. "Every doctor ought to be taught the simple techniques of hypnosis," he told the annual meeting of the American Association for the Advancement of Science in Boston yesterday.
"It's thought to be something that takes away control from a patient, but it's actually something that enhances their own self control. So you can teach people how to manage their anxiety, how to manage their pain and they are grateful for it."
The study involved scanning the brains of eight hypnotised volunteers who were first screened to see how susceptible they were to hypnosis. About half the population could be hypnotised to a moderate extent, and about 10 per cent were "highly hypnotisable", the scientists found.
The subjects were made to look at a grid of patterns that could be turned from black and white into colour. When hypnotised, they were asked to imagine colours when there were none, and black and white when there were colours. A brain scanner was used to measure blood flow to certain regions of the subject's brain, such as the fusiform gyrus, which is involved in processing the visual information relating to coloured images. Professor Spiegel said: "What we found is that, as we predicted, when the highly hypnotisables thought they were seeing colour but were seeing black and white, there was an increase in the blood flow in the fusiform gyrus.
"And when they thought they were seeing black and white but were really seeing in colour, there was a decrease in blood flow. So believing was seeing.
"In fact when they believed they were looking at colour, the part of their brain that processes colour vision showed increased blood flow and when they believed they were looking at black and white it showed decreased blood flow."
The findings cannot be explained by the simple "power of persuasion" that some sceptics have used to discredit hypnosis, Professor Spiegel said. "They [the volunteers] are not just telling you what you want to hear, they are actually able to change the way the brain perceives information and that has tremendous therapeutic potential. This is scientific evidence that something unusual happens in the brain that doesn't happen ordinarily when people are hypnotised. There's been a whole school of argument that hypnosis is nothing more than an exaggerated form of social compliance, that people are just telling you what you think you want to hear."
Professor Spiegel has used hypnosis on adults and children having painful medical procedures. One such operation on children involves inserting a catheter into the bladder, which has to be done without anaesthetics because it requires the co-operation of the patient.
"It's a horrible procedure. We're now doing a randomised trial comparing teaching the kids self-hypnosis – I have them imagining they are going to Disneyland – versus doing just standard care," he said.
"We're finding so far similar results to what we've seen in adults. There is less crying, less pain as the doctors are inserting the catheter and the procedure takes 20 minutes less."Reuse content