August 26, 2009

The Placebo Effect is Stronger than Ever

The September 2009 issue of Wired has a terrific article about the placebo effect / response. Steve Silberman writes in "Placebos Are Getting More Effective. Drugmakers Are Desperate to Know Why" that the placebo effect in drug clinical trials has been increasing in recent years, causing many trials to "cross the futility boundary" where drugs are no more effective than a placebo.

Silberman writes: "It's not that the old meds are getting weaker, drug developers say. It's as if the placebo effect is somehow getting stronger."

This is not good for drug manufacturers, of course, but it is fascinating for cognitive science aficionados. Some of the points Silberman raises in the article:
  • Previously effective Prozac has recently tested as less effective against placebos;
  • Antidepressant effectiveness compared with placebos differs by geographic region;
  • Perhaps the increase in drug advertising has affected people's expectation of what drugs will do, thus leading to an increase in the placebo effect.
Italian researcher Fabrizio Benedetti, at the University of Turin, has done research showing that "Alzheimer's patients with impaired cognitive function get less pain relief from analgesic drugs than normal volunteers do." Benedetti speculates that Alzheimer's patients can't anticipate the treatment and so only feel the actual effect of the drug, rather than anticipating its effects.

There is a data-mining effort underway, supported by the NIH, called the Placebo Response Drug Trials Survey, in which psychiatrist William Potter and colleagues from many drug firms are trying to "determine which variables are responsible for the apparent rise in the placebo effect." (Silberman notes that the "existence of the project ... is being kept under wraps" -- which is consistent with my experience, as a Google / literature search for "Placebo Response Drug Trials Survey" resulted in no hits.)

Silberman provides a great definition of the phenomenon: "one way that placebo aids recovery is by hacking the mind's ability to predict the future." I enjoyed the article and can't wait to hear more.

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