Thrill-seekers more sensitive to placebo effect?
Are adrenaline junkies extra sensitive to the placebo effect?
Researchers at McGill University set out to test that hypothesis by causing pain in the legs of 22 volunteers with a harmless saline infusion.
The subjects were told that they were getting an experimental analgesic cream on one leg and plain lotion on the other. In fact, they all got lotion on both sides.
The subjects were asked how much pain they felt in each leg. Those who said the "active" leg hurt less than the "inert" leg were deemed to be enjoying a placebo effect. The bigger the difference, the stronger the placebo for that person:
Not everyone got pain relief from the placebo, but those that did scored higher on tests that gauge sensation-seeking personalities. These characteristics explained about a third of the differences in placebo responses between volunteers.
"The fact that they show a pretty strong correlation between a personality trait and strength of placebo response, I do find interesting," says Jon Stoessl, a neurologist at the University of British Columbia, who has studied placebo response in patients with Parkinson's disease. [New Scientist]
This is the first study to link personality and placebo. Obviously, this research program is in its early stages. Still, the idea that subconscious motivation can boost the placebo effect is provocative both empirically and philosophically.
The authors of the saline study surmised that thrill seekers have greater subconscious motivation to achieve the placebo effect because they are more motivated to seek out rewards in general. Pain researchers have reason to believe that the brain processes pain relief as a reward in itself as opposed to simply registering the end of a punishment.
Stossel cautions that an individual's placebo sensitivity can vary depending on circumstances, which suggests that personality isn't the whole story.