Double-blind placebo-controlled provocation study in patients with subjective Multiple Chemical Sensitivity (MCS) and matched control subjects
Introduction. Multiple Chemical Sensitivity (MCS) is an acquired disorder with recurrent symptoms referable to multiple organ systems. No widely accepted test of physiologic function correlates with symptoms and it has not been recognized as a distinct entity by the scientific community. Few double-blind placebo-controlled studies have been done. The objectives of this study were to test two hypotheses: that patients with MCS can distinguish reliably between solvents and placebo, and that there are significant differences in objective biological and neuropsychological parameters between solvent and placebo exposures. Methods. Twenty patients with MCS and 17 controls under-went six exposure sessions (solvent mixture and clean air in random order, double-blind) in a challenge chamber. Positive reactions were defined as subjective perception of being exposed to solvents, blood pressure or heart rate change of> = 10%, rash or clinical signs of hypoxia, or symptom severity rise after exposure. Results. No differences between the groups with regard to sensitivity, specificity, and accuracy were found. Cognitive performance was not influenced by solvent exposure, and did not differ between the groups. There was no difference between the groups in serum cortisol levels measured before and after exposures. Conclusion. The hypotheses were not confirmed.