Placebo response in asthma: A robust and objective phenomenon

Published assertions that only subjective aspects of asthma, such as dyspnea, respond to placebo do not concur with the collective experience of clinicians and researchers. Asthma has long been believed to have a psychosomatic component; recent studies linking ''stress'' to increased asthma severity support the role of disease-relevant mind-body links. Despite the availability of objective measures of asthma activity, few investigators have chosen to study placebo in asthma. In this issue of the Journal, Kemeny and coauthors (p 1375) report on the placebo response in mild asthma, modulating bronchial hyperreactivity as measured by a methacholine inhalation challenge. They found in a randomized, double-blind study that pretreatment with a placebo (drug-free) inhaler resulted in nearly a doubling of methacholine PC20 compared with baseline, almost one third of the improvement that followed salmeterol inhalation (see Figure). These findings validate the existence of an objective and large placebo response in asthma. They also provide a model system to study specific brain pathways that are responsible for processing perceived stimuli to modulate physiologic responses. Understanding the placebo response may also lead to novel therapeutic approaches to asthma and other diseases; such treatment, after all, is likely to induce adverse effects ''no worse than placebo''