Wired's Steve Silberman explores the fascinating and increasingly important placebo effect, which appears to be getting stronger:
The upshot is fewer new medicines available to ailing patients and more financial woes for the beleaguered pharmaceutical industry. Last November, a new type of gene therapy for Parkinson's disease, championed by the Michael J. Fox Foundation, was abruptly withdrawn from Phase II trials after unexpectedly tanking against placebo. A stem-cell startup called Osiris Therapeutics got a drubbing on Wall Street in March, when it suspended trials of its pill for Crohn's disease, an intestinal ailment, citing an "unusually high" response to placebo. Two days later, Eli Lilly broke off testing of a much-touted new drug for schizophrenia when volunteers showed double the expected level of placebo response...
Part of the problem was that response to placebo was considered a psychological trait related to neurosis and gullibility rather than a physiological phenomenon that could be scrutinized in the lab and manipulated for therapeutic benefit. But then Benedetti came across a study, done years earlier, that suggested the placebo effect had a neurological foundation. US scientists had found that a drug called naloxone blocks the pain-relieving power of placebo treatments. The brain produces its own analgesic compounds called opioids, released under conditions of stress, and naloxone blocks the action of these natural painkillers and their synthetic analogs. The study gave Benedetti the lead he needed to pursue his own research while running small clinical trials for drug companies.
Now, after 15 years of experimentation, he has succeeded in mapping many of the biochemical reactions responsible for the placebo effect, uncovering a broad repertoire of self-healing responses. Placebo-activated opioids, for example, not only relieve pain; they also modulate heart rate and respiration. The neurotransmitter dopamine, when released by placebo treatment, helps improve motor function in Parkinson's patients. Mechanisms like these can elevate mood, sharpen cognitive ability, alleviate digestive disorders, relieve insomnia, and limit the secretion of stress-related hormones like insulin and cortisol.
In one study, Benedetti found that Alzheimer's patients with impaired cognitive function get less pain relief from analgesic drugs than normal volunteers do. Using advanced methods of EEG analysis, he discovered that the connections between the patients' prefrontal lobes and their opioid systems had been damaged. Healthy volunteers feel the benefit of medication plus a placebo boost. Patients who are unable to formulate ideas about the future because of cortical deficits, however, feel only the effect of the drug itself. The experiment suggests that because Alzheimer's patients don't get the benefits of anticipating the treatment, they require higher doses of painkillers to experience normal levels of relief.