Placebos can make us feel better. Mild electric zaps to the brain can make that effect even stronger, scientists report online May 3 in Proceedings of the National Academy of Sciences. The finding raises the possibility of enhancing the power of expectations to improve treatments.
This is the first study to boost placebo and blunt pain-inducing nocebo effects by altering brain activity, says Jian Kong, a pain researcher at Massachusetts General Hospital in Charlestown.
The placebo effect arises when someone feels better after taking an inactive substance, like a sugar pill, because they expect the substance to help. The nocebo effect is the placebo’s evil twin: A person feels worse after taking an inactive substance that they expect to have unpleasant effects.
To play with people’s expectations, Kong’s team primed 81 participants for painful heat. The heat was delivered by a thermal stimulator to the forearm while participants lay in a functional MRI scanner. Each person received three creams, each to a different spot on their arms. One cream, participants were told, was a numbing lidocaine cream, one was a regular cream and one was a pain-increasing capsaicin cream. But in fact, all the creams were the same inert lotion, dyed different colors.