Psychogenic origins of multiple chemical sensitivities syndrome: a critical review of the research literature.

The purpose of this review was to critically evaluate research on the psychogenic origins of multiple chemical sensitivities (MCS) syndrome. Using as keywords environmental illness, multiple chemical sensitivities, and clinical ecology, two databases--PsychLit and Medline--were searched by computer; reference lists of all articles located were also searched manually. Ten articles meeting three criteria were selected for review. Five sample selection problems, seven measurement problems, and three study design problems were common in all but one of the articles reviewed. Current studies investigating psychogenic hypotheses of MCS syndrome are methodologically problematic and their conclusions questionable. Studies of psychiatric profiles observed in MCS syndrome need to be designed to differentiate between competing psychogenic and biogenic hypotheses.