The Placebo Effect: A Mystery in Potential Therapy

Today’s “gold standard” of drug testing is the double-blind, randomized controlled trial (RCT). In an RCT, some of the patients receive the actual drug; others receive a placebo. Neither the researchers nor the patients know who gets the drug and who gets the placebo, hence the “double-blind.” Experts won’t approve a drug if it is not more effective than a placebo.

Researchers have observed placebos producing changes in blood pressure and heart rate, as well as relieving pain, depression, anxiety and irritable bowel syndrome. Sham injections seem to work better than sham pills, large pills work better than small ones, and two pills are better than one. 

In one study, a surgeon gave patients a sham knee surgery, where the surgeon made an incision, but did nothing to the knee before sewing it back up. The patients were just as likely to find relief as those who underwent the procedure.

It’s still a mystery how the placebo effect works. Some say it’s a matter of expectations. Some think it’s classical conditioning at work. We’re conditioned to feel better after taking medicine, so we do. The placebo effect on pain could be activating natural opioids in the brain as a response to the relationship between the physician and patient.

But one thing is not a mystery. For all the good a placebo might do, lying to patients is not ethical. In clinical trials, the participants know that they may be in the group that gets a placebo.

However, experts could take advantage of the placebo effect without fraud — pious or otherwise. One of the most intriguing things about placebos is that they can work even when patients know they’re getting a placebo.