Polluted places or polluted minds? An experimental sham-exposure study on background psychological factors of symptom formation in 'Idiophatic Environmental Intolerance attributed to electromagnetic fields'.

Introduction: 'Idiophatic Environmental Intolerance attributed to electromagnetic fields' (IEI-EMF) refers to the perception of subjective symptoms during or following EMF exposure. IEI-EMF has become disproved to be a mostly biologic entity by now, and evidences accumulate to support the role of nocebo effect in the phenomenon. The two aims of this study were to demonstrate the significant role of the nocebo effect in physical symptoms reported at 50Hz frequency of EMF exposure, as well as to explore some psychological factors which may predispose to IEI-EMF.

Methods: A total of 40 volunteer university students have completed a battery of psychological questionnaires (expectations; IEI-EMF; state anxiety - STAI-S; dispositional optimism - LOT-R; somatisation - PHQ-15; somatosensory amplification - SSAS) before, and checklists of physical symptoms during sham exposure to "weak" and "strong" EMFs, respectively. Participants were also asked about the extent to which they had perceived the presence of the presumed EMF.

Results: Participants with higher IEI-EMF scores expected and experienced more symptoms. Suggestion of stronger EMF exposure resulted in larger symptom scores and enhanced EMF-perception as compared to the presumed weaker exposure. Experienced symptom scores were predicted primarily by somatisation scores, whereas self-rating of IEI-EMF was predicted by somatosensory amplification scores.

Conclusion: The results confirm that there is considerable nocebo effect in symptom reports related to 50Hz frequency EMFs. IEI-EMF seems to be formed through a vicious circle of psychosocial factors, such as enhanced perception of risk and expectations, self-monitoring, somatisation and somatosensory amplification, causalization and misattribution.