Objective: To understand idiopathic environmental intolerances (IEI)-formerly multiple chemical sensitivities (MCS)-it is helpful to outline its characteristic psychiatric morbidity.
Method: We applied a standardized interview according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (SCID) to 305 environmental patients with and without IEI.
Results: Somatoform, affective and anxiety disorders were the most frequent diagnoses but only slightly differed between patients with or without IEI. In both groups, current substance-related disorders were rare. We found a clearly higher prevalence of psychotic, especially current delusional disorders, in IEI.
Conclusion: Somatization, depression, and anxiety are frequent in IEI but nonspecific. Psychotic disorders are more common in IEI than in other types of environmental illness. It appears worthwhile to study personality and cognitive style to explain the pivotal features of IEI.