Wired has published what must be one of the most comprehensive articles looking at the phenomenon of the placebo effect.
From its humble beginnings in WWII with anesthetist Henry Beecher to the placebo’s transition from being treated as a purely psychological trait to a physiological one; there’s some great material here.
Two comprehensive analyses of antidepressant trials have uncovered a dramatic increase in placebo response since the 1980s. One estimated that the so-called effect size (a measure of statistical significance) in placebo groups had nearly doubled over that time.
It’s not that the old meds are getting weaker, drug developers say. It’s as if the placebo effect is somehow getting stronger.
The fact that an increasing number of medications are unable to beat sugar pills has thrown the [pharmaceutical] industry into crisis. The stakes could hardly be higher. In today’s economy, the fate of a long-established company can hang on the outcome of a handful of tests.
Related: Placebo in History.
Can the placebo effect work with exercise and fitness? Two Harvard psychologists decided to find out, and the results were startling.
84 maids at seven carefully matched hotels [were quizzed on] how much exercise they got. Fully a third of the women said they got no exercise at all, while two-thirds said they did not work out regularly. Langer and Crum took several measures of the women’s basic fitness levels, which indicated that they, indeed, had the poor health of basically sedentary people. Then just over half the women were told an unfamiliar truth: cleaning 15 rooms daily â€” pushing recalcitrant vacuum cleaners, scrubbing tubs, pulling sheets â€” constitutes more than enough activity to meet the surgeon general’s recommendation of a half-hour of physical activity daily. [The] control group was left in the dark.
A month later, Langer and Crum checked back with the women to find, as they reported in the February issue of Psychological Science, remarkable results. The average study-group maid had lost 2 pounds, while her systolic blood pressure had dropped by 10 points; by all measures the 44 women “were significantly healthier.” Yet there were no reported changes in behavior, only in mind-set.
The accompanying graphic highlights the findings, and the story was also covered by Ben Goldacre in his Guardian column, Bad Science.
I’ve just written a post on one of my favourite topics; the placebo effect.
Triggered by the article Placebo is not what you think, it touches on the use of placebos by medical professionals (currently a banned practice) and the informed use of placebos by heroin addicts. Strangely enough, in the latter case the use by addicts is self-medicated:
Furthermore, studies done in the 1970s showed that when heroin users inject water (sometimes done deliberately to alleviate cravings when drugs are in short supply), they can experience drug-like euphoria and have been observed to show opiate-like physiological signs such as pupil constriction.
This last point also demonstrates that placebo is not solely about expectancy, belief or ‘being fooled’, as the heroin users knew they were injecting themselves with water. Conditioned responses play a role.