I'm Katherine Cole with the VOA Special English Health Report.

Studies of new drugs traditionally involve at least two groups of people.  The people in one of those groups are given only what they think is the drug.  Really they get a placebo -- an inactive substance.  The drug is proven effective if it performs better than the placebo. 

Some researchers do not think drug studies should use placebos.  They say it makes more sense to compare new medicines to drugs already on the market.  Then people would know if a new drug is any better.

"Placebo” is Latin for “I shall please.”  It may contain nothing more than sugar. 

Yet some people who are given a placebo experience improvements in their health.  This is called the placebo effect.

Some doctors use the placebo effect in their treatments.  An influential study published in nineteen fifty-five said placebo treatments made patients feel better thirty-five percent of the time. 

But in two thousand one, Danish researchers reported that they had examined more than one hundred studies.  They found little evidence of healing as a result of placebos.

Still, there is continued belief in the placebo effect.

A Swedish study published last year suggested that a placebo can reduce the emotional effects of unpleasant experiences.  The study involved people who looked at images of dead bodies and other unpleasant pictures.  The findings appeared in the journal Neuron.

The researchers said the effects in the brain were similar to those seen when placebos have been used as a pain treatment.  In both cases, they said, expectations of improvement are a major influence.

But more than expectations might explain why placebos appear effective sometimes. 

Researchers led by Scot Simpson at the University of Alberta, in Canada, just had a report published in the British Medical Journal.  They examined twenty-one studies.  These compared death rates between patients who always took their medicine and those who did not. 

Even patients who took placebos had better results than those who did not follow doctor's orders.  The researchers see this finding as support for the idea of a so-called healthy adherer effect.  That is, a person who takes a drug treatment as directed may also do other things to live a healthy life.

And that is the VOA Special English Health Report.  You can download free transcripts and MP3 files of our weekly reports at voaspecialenglish.com.  I'm Katherine Cole.