The "placebo response" occurs when a person who is ill perceives an improvement or actually experiences an improvement in symptoms or overall health from the psychological effect of receiving treatment rather than from the treatment itself. Many factors influence the generation of a placebo response. Some scientists believe that certain psychological factors actually cause the body to produce hormones called endorphins, which act as the body's own pain killers, resulting in reduced levels of pain or discomfort.
The placebo response may be due to a person's profound desire to get better, increased medical attention as result of being in an experimental study of a new treatment, or even an unconscious wish by the person to please the physician by getting better.
The Problem with the Placebo Response
Some improvements triggered by the placebo effect can be measured objectively. To that extent they are as real as any other improvement. But studies have demonstrated that placebo effects are rarely as strong as the effects of a medically valuable treatment. Moreover, placebo effects diminish over time even if the individual continues with the treatment that elicited them. Read the latest on the ethics of placebo controls in MS clinical trials
The Need to Build Controls into Studies
The widespread existence of the placebo response reinforces the need to build adequate controls for this response into the design of clinical trials of any new treatment or therapy, so that the actual therapeutic response to a treatment being tested can be separated from responses resulting from the placebo effect.
In some trials, up to 70% of MS patients have demonstrated a placebo response. Therefore, in order to be considered as an effective treatment, an agent must be demonstrated to have produced statistically significant benefit in the patients who received it, over and above the benefit experienced by a similar group of patients who received a placebo.