I have been fascinated by placebos ever since the late Pat Wall gave a talk about them at a symposium on consciousness in the early Nineties. It was very small and very select; the report of the procedings costs an astonishing $160, and I am atill not quite sure how I was smuggled in there. We had Dennett, Searle, Tom Nagel, Tony-Marcel-who-cannot-stop-talking, Nick Humphrey, Maggie Boden, Colin McGinn …
In any case, Wall gave a wonderful talk about placebos which cured me forever of the temptation to suppose that consciousness can be an epiphenomenon. The point is that placebos work only when people consciously and whole-heartedly believe in them. Then they produce changes in thebody’s working far below the level of consciousness. They don’t just remove pain. They remove inflammation. Placebo treatment of heart patients improves their performace on the treadmill.
One of the stories he told, which is now a classic, was of a doctor in the Korean War, who developed acute appendicitis during a surgical marathon and had his nurse inject him with morphine so he could go onworking before going onto the table himself. Only after his own surgery did he discover that they had run out of morphine, and she had shot him up with saline solution instead. Yet the pain had vanished completely, and he had been able to work for another two hours.
Now comes the most astonishing twist on this experiment, from the New Scientist.
DON’T try this at home. Several times a day, for several days, you induce pain in someone. You control the pain with morphine until the final day of the experiment, when you replace the morphine with saline solution. Guess what? The saline takes the pain away.
This is the placebo effect: somehow, sometimes, a whole lot of nothing can be very powerful. Except it’s not quite nothing. When Fabrizio Benedetti of the University of Turin in Italy carried out the above experiment, he added a final twist by adding naloxone, a drug that blocks the effects of morphine, to the saline. The shocking result? The pain-relieving power of saline solution disappeared.
Wall himself died of cancer, a few years back. I talked to him while he was in remission. The pain of cancer, he said, serves no useful purpose at all.