Expensive Placebos Show Better Results Than Cheap Ones

A new study reveals that when patients with Parkinson's disease (PD) received an injection described as an effective drug costing USD 1,500 per dose, their motor function improved significantly more than when they got one supposedly costing just USD 100.

Researchers at the University of Cincinnati (UC, OH, USA), the University of Toronto (Canada), and other institutions conducted a prospective double-blind study in 12 patients with moderate to severe PD and motor fluctuations who were randomized to a cheap or expensive subcutaneous "novel injectable dopamine agonist" (in reality a normal saline placebo); the patients were crossed over to the alternate arm approximately after four hours. Measurements of brain activity were performed using a feedback-based visual-motor associative learning functional magnetic resonance imaging (fMRI) task.

The researchers found that although both placebos improved motor function, benefit was greater when patients were randomized first to the expensive placebo, with a magnitude halfway between that of cheap placebo and levodopa. Brain activation was greater upon first-given cheap placebo, but not upon first-given expensive placebo or levodopa. Regardless of the order of administration, only cheap placebo increased brain activation in the left lateral sensorimotor cortex, as well as other regions. The study was published on January 28, 2015, in Neurology.

“Expensive placebo significantly improved motor function and decreased brain activation in a direction and magnitude comparable to, albeit less than, levodopa,” said lead author neurologist Alberto Espay, MD. “When the volunteers were debriefed, eight said they expected the expensive drug to be more effective; they experienced the greatest improvement relative to the cheap injection. Four said they had no expectation of greater benefits, and they showed little overall changes in motor function.”

The placebo—Latin for “I will please”—effect is a phenomenon wherein about one third of those taking a placebo for various complaints (including pain, headache, and seasickness) will experience relief from symptoms. The underlying mechanism remains mysterious, but the effect has been attributed to many things, such as regression to the mean, spontaneous improvement, reduction of stress, misdiagnosis in the first place, subject expectancy, classical conditioning, and more.

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