Syndrome stability and psychological predictors of symptom severity in idiopathic environmental intolerance and somatoform disorders.
BACKGROUND
Previous studies suggest that idiopathic environmental intolerance (IEI) is a variant of somatoform disorders (SFDs) or the so-called functional somatic syndromes. Little is known, however, about the stability and the psychological predictors of IEI.


METHODS
This prospective study examined the 1-year stability of somatic symptoms and IEI features in three diagnostic groups: 49 subjects with IEI, 43 subjects with SFD but without IEI, and 54 subjects (control group, CG) with neither IEI nor SFD. The predictive value of typical psychological predictors for somatization was tested using zero-order correlations and multiple linear regression analyses.


RESULTS
Somatic symptoms and IEI features proved to be temporally stable over the 1-year follow-up period. The SFD and IEI groups scored significantly higher than CG on all measures of somatic symptoms and on questionnaires assessing psychological predictors for somatization. Measures of trait negative affectivity (NA), somatic symptom attribution and somatosensory amplification predicted somatic symptom severity within the IEI and SFD groups, both at baseline and 1 year later. The strongest predictors of IEI complaints in the IEI group were somatic attributions, followed by prominent cognitions of environmental threat and a tendency to focus on unpleasant bodily sensations and to consider them as pathological.


CONCLUSIONS
IEI and SFD are highly stable conditions. In both SFD and IEI, NA and the processes of symptom perception, interpretation and attribution contribute substantially to the persistence of typically somatoform symptoms and IEI complaints. Treatment of IEI and SFD should address these psychological factors and mechanisms.
Bailer
Josef
J
Department of Clinical Psychology, Central Institute of Mental Health, Mannheim, Germany. bailer@zi-mannheim.de
Witthöft
Michael
M
Bayerl
Christiane
C
Rist
Fred
F
D000328:Adult; D000704:Analysis of Variance; D004777:Environment; D005260:Female; D005500:Follow-Up Studies; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010465:Perception; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D012903:Smell / Q000502:physiology; D013001:Somatoform Disorders / Q000523:psychology*; D011795:Surveys and Questionnaires; D013577:Syndrome