The Strange Powers of the Placebo Effect

The placebo effect is well known but not widely understood. This is a nice summary of how its effectiveness varies in strange ways.

Generic drugs, the placebo effect and the White Stripes

The placebo effect has been well documented in medicine. It takes various forms, in Italy (home of the Azzuri) blue pills are particularly effective. In randomized controls trials the efficacy of drugs are often measured relative to that of placebos. Sham pills, sham surgery and sham acupuncture seem to be quite effective at times and may explain the success of alternative treatments like homeopathy which is based on psuedo-science. Similarly, branded drugs have been reported to be more effective than generics. What people expect or have faith in, is important.
The most entertaining, if not the most erudite, discussion of this phenomenon is the White Stripes' "Girl you Have no Faith in Medicine" from their album Elephant. For example:
Is there a way to find the cure for this
Implanted in a pill?
Is it just the name upon the bottle
That determines if it will?

Is the problem you're allergic
To a well familiar name?
Do you have a problem with this one
If the results are the same?

What's the placebo effect worth?

Earlier this year a study in the BMJ examining pain relief from analgesics showed that just informing people that a codeine product they were taking (actually a placebo) was worth $2.50rather than 10 cents increased the proportion of people who reported pain relief from 61% to 85.4%.So reducing the "price" of the placebo may have reduced the pain relief induced.

Waber RL, Shiv B, Carmon Z, Ariely D. Commercial features of placebo and therapeutic efficacy. JAMA 2008;299:1016-7.

A second more recent study by Kaptchuk et al. (2008)has shown a 'dose dependence' of placebo effects on pain relief dependent on if the patient was assigned to a waiting list (observation), placebo acupuncture alone ("limited"), or placebo acupuncture with a patient-practitioner relationship augmented by warmth, attention, and confidence ("augmented"). The proportion of patients reporting adequate relief were 28% on waiting list, 44% in limited group, and 62% in augmented group (P<0.001 for trend).

So it does appear that the placebo effect is still with us despite calls for it's demise though separating the effects of therapeutic rituals, patient-practitioner interaction, observation/assessment (or the “Hawthorne effect”, initially describing “an increase in worker productivity produced by the psychological stimulus of being singled out and made to feel important”) or investment in ones health, an explanation which seems plausible from the Ariely study.

Is the benefit of exercise a placebo effect?

The next time you're doing the housework, try donning a tracksuit, cranking up the Rocky sound-track and viewing the whole thing as an exercise session - doing so could have a positive effect on your health.

That's according to Alia Crum and Ellen Langer, who assessed the health of 84 female hotel cleaners, all of whom worked between 32 to 40 hours per week, cleaning approximately 15 rooms per day.

The researchers then told half the cleaners, via verbal presentations, handouts and posters, that the cleaning work they perform counts as exercise and means they effectively lead an active lifestyle, easily fulfilling government recommendations for daily exercise. The remaining cleaners acted as controls.

A month later the health of the cleaners was assessed again. Crucially, those who had been reminded how much exercise they engage in at work, showed health improvements in terms of weight, body mass index, body-fat, waist-to-hip ratio and blood pressure. The control cleaners showed no such improvements.

What caused this health boost? Those cleaners reminded that their work counted as exercise didn't change their smoking, drinking or eating habits over the month, nor did they start exercising more in their spare time. However, as intended, the intervention did lead them to perceive that they engaged in more exercise at work.

"These results support our hypothesis that increasing perceived exercise independently of actual exercise results in subsequent physiological improvements", the researchers said.

In the same way that some medicines work not because of any particular ingredient, but because of patients' belief in their healing power, the researchers concluded their findings show some of the benefits of exercise are also related to beliefs - otherwise known as the placebo effect.
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Crum, A.J. & Langer, E.J. (2007). Mind-set matters. Exercise and the placebo
effect. Psychological Science, 18, 165-171.
http://dx.doi.org/10.1111/j.1467-9280.2007.01867.x