Idiopathic environmental intolerance: Part 1: A causation analysis applying Bradford Hill's criteria to the toxicogenic theory

Somatic and mental distress as predictors of number of symptoms associated with environmental factors in an adult general population: Cross-sectional and longitudinal findings

OBJECTIVE

Hypotheses were tested of associations between indicators of somatic and mental distress and number of different types of environmental intolerances, referred to as symptoms attributed to environmental factors (SAEFs), and these indicators predicting development of additional SAEFs in a general population. The SAEFs regarded chemicals, buildings, electromagnetic fields and sounds.

METHODS

Data were used from a Swedish population-based sample of 2336 adults. Cross-sectional and 3-year longitudinal analyses were conducted based on validated questionnaire instruments assessing somatic symptom distress, perceived stress, anxiety and depression.

RESULTS

Prevalence percentage of the SAEFs ranged from 2.1 % to 13.4 %; 16.2 % had one SAEF, 4.9 % had two SAEFs, and 1.2 % had three or four SAEFs. Cross-sectionally, Kendall rank correlation analyses and ANOVAs showed that somatic symptom distress (rtau-b = 0.214), perceived stress (rtau-b = 0.137), anxiety (rtau-b = 0.145) and depression (rtau-b = 0.100) increased with number of SAEF. In the longitudinal analysis, all four indicators were found to be predictors of an increase in number of SAEFs three years later (odds ratios = 1.021-1.049 for each scale step), with somatic symptom distress as the strongest predictor.

CONCLUSION

The results suggest that all four types of SAEFs are associated with all four indicators of negative affectivity, and that the level of these indicators is associated with number of SAEFs and predict development of additional SAEFs. Among the studied indicators, somatic symptom distress appears to be particularly associated with development of multiple SAEFs, perhaps driven by the motive to find a cause for bothersome symptoms (misattribution).

Multiple Chemical Sensitivity: A Clinical Perspective

OBJECTIVE

The etiology of multiple chemical sensitivity (MCS) is still debated, which is an obstacle to assessing treatment options. An analysis of the scientific literature combined with the clinical experience can suggest some avenues.

METHODS

The etiology of MCS and its underlying mechanisms were reviewed from the scientific literature to identify the main factors contributing to its development. The results of the studies involving biomarkers and cerebral imaging techniques on MCS subjects were compared with those performed on subjects having the comorbidities of MCS. From the scientific literature and the experience in a clinical setting in occupational and environmental medicine, distinct types of MCS were looked for, with the application of the underlying mechanisms. The potential effectiveness of available treatments was also reviewed.

RESULTS

Among many factors, unresolved emotional traumas causing chronic and acute stress reactions play an important role in the development of MCS and can be the basis for effective treatment. We identified three types of clinical presentations, called the accidental type, following a toxic exposure causing an associated emotional trauma, the associative type, following a repeated innocuous exposure in a threatening context, and the developmental type, following a traumatic childhood/adolescence causing hypervigilance and chronic stress/trauma-related disorders. We presented real cases to illustrate these types and the mechanisms behind their development, as well as effective resolution.

CONCLUSIONS

MCS and its comorbidities could be treated effectively when the underlying emotional trauma(s) are targeted using trauma-focused psychotherapy and other therapies. Diagnostic criteria, principles of treatment and prevention, and avenues for research were derived from this analysis.

Do somatic symptom distress and attribution predict symptoms associated with environmental factors?

OBJECTIVE

Not much is known on the development of symptoms associated with environmental factors (SAEF), also known as (idiopathic) environmental intolerances. Findings from qualitative studies suggest that appearance of symptoms might be the first step, followed by the acquisition of a specific attribution. The current study investigated cross-sectional and longitudinal (three years) associations between attribution and symptoms with respect to symptoms associated with chemical substances, certain indoor environments (buildings), sounds, and electromagnetic fields (EMFs).

METHODS

We used data from the first two waves of the population-based Västerbotten Environmental Health Study (n = 2336). Participants completed the Patient Health Questionnaire Somatic Symptom Scale (PHQ-15), the Environmental Symptom-Attribution Scale, and answered single questions on the four aforementioned SAEFs.

RESULTS

Using binary logistic regression analyses, all four SAEFs showed significant cross-sectional associations with somatic symptom distress and the respective attribution. In the longitudinal analysis, development of SAEF-Sound and SAEF-Chemicals were predicted by both somatic symptom distress and attribution. SAEF-EMFs was predicted only by attribution, whereas neither somatic symptom distress nor attribution forecasted SAEF-Buildings.

CONCLUSION

Overall, these findings suggest that attribution (i.e., a specific expectation) plays a substantial role in the development and maintenance of many SAEFs.

Multiple Chemical Sensitivity/Idiopathic Environmental Intolerance: A Practical Approach to Diagnosis and Management

Patients with multiple chemical sensitivity, now called idiopathic environmental intolerance, frequently present to clinical immunologists and allergists for diagnosis and treatment. Patients report a plethora of respiratory and multisystem problems attributed to a wide variety of unrelated, otherwise non-noxious, triggers. They may go to extreme, often seemingly bizarre lengths to avoid contact with everyday exposures and may become housebound, unable to work or function socially. Often beginning with exposure to odors, triggers can multiply to involve foods, clothing, medications, and even electromagnetic radiation. The condition cannot be explained by IgE-mediated or other immune processes, and clinical immunologists and allergists may feel unprepared to care for such patients. In this article, a paradigm to understand the probable mechanisms underlying this condition and a practical approach to diagnosis and management will be presented.

An idiographic approach to idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) part I. Environmental, psychosocial and clinical assessment of three individuals with severe IEI-EMF

IEI-EMF refers to an environmental illness whose primary feature is the occurrence of symptoms that are attributed to exposure to weak electromagnetic fields (EMFs). There is a growing evidence that this condition is characterized by marked individual differences thus a within-subject approach might add important information beyond the widely used nomothetic method. A mixed qualitative/quantitative idiographic protocol with a threefold diagnostic approach was tested with the participation of three individuals with severe IEI-EMF. In this qualitative paper, the environmental, psychosocial, and clinical aspects are presented and discussed (results of ecological momentary assessment are discussed in Part II of this study). For two participants, psychopathological factors appeared to be strongly related to the condition. Psychological assessment indicated a severe pre-psychotic state with paranoid tendencies, supplemented with a strong attentional focus on bodily sensations and health status. The psychological profile of the third individual showed no obvious pathology. Overall, the findings suggest that the condition might have uniformly been triggered by serious psychosocial stress for all participants. Substantial aetiological differences among participants with severe IEI-EMF were revealed. The substantial heterogeneity in the psychological and psychopathological profiles associated with IEI-EMF warrants the use of idiographic multimodal assessments in order to better understand the different ways of aetiology and to facilitate person-taylored treatments.

Psychological models of development of idiopathic environmental intolerances: Evidence from longitudinal population-based data

The origin of idiopathic environmental intolerances (IEIs) is an open question. According to the psychological approaches, various top-down factors play a dominant role in the development of IEIs. The general psychopathology model assumes a propensity towards mental ill-health (negative affectivity) increases the probability of developing IEIs. The attribution model emphasizes the importance of mistaken attribution of experienced somatic symptoms; thus, more symptoms should lead to more IEIs. Finally, the nocebo model highlights the role of expectations in the development of IEIs. In this case, worries about the harmful effects of environmental factors are assumed to evoke IEIs. We estimated cross-lagged panel models with latent variables based on longitudinal data obtained at two time points (six years apart) from a large near-representative community sample to test the hypothesized associations. Indicators of chemical intolerance, electromagnetic hypersensitivity, and sound sensitivity fit well under a common latent factor of IEIs. This factor, in turn, showed considerable temporal stability. However, whereas a positive association was found between IEIs and increased somatic symptoms and modern health worries six years later, the changes therein could not be predicted as hypothesized by the three psychological models. We discuss the implications of these results, as well as methodological aspects in the measurement and prediction of change in IEIs.

Italian Expert Consensus on Clinical and Therapeutic Management of Multiple Chemical Sensitivity (MCS)

Multiple chemical sensitivity (MCS) is a multisystem, recurrent, environmental disorder that flares in response to different exposures (i.e., pesticides, solvents, toxic metals and molds) under the threshold limit value (TLV) calculated for age and gender in the general population. MCS is a syndrome characterized by cutaneous, allergic, gastrointestinal, rheumatological, endocrinological, cardiological and neurological signs and symptoms. We performed a systematic review of the literature to summarize the current clinical and therapeutic evidence and then oriented an eDelphi consensus. Four main research domains were identified (diagnosis, treatment, hospitalization and emergency) and discussed by 10 experts and an MCS patient. Thus, the first Italian MCS consensus had the double aim: (a) to improve MCS knowledge among healthcare workers and patients by standardizing the clinical and therapeutic management to MCS patients; and (b) to improve and shed light on MCS misconceptions not supported by evidence-based medicine (EBM).

Establishing a causal link between social relationships and health using the Bradford Hill Guidelines

An abundance of evidence suggests that the size and quality of our social relationships improves humans' physical and mental health while increasing lifespan. However most of this evidence comes from observational rather than experimental (randomised trial) evidence, leaving open the possibility that the connection between social relationships and health could be associational rather than causal. However there are examples, including the link between smoking and lung cancer, where a cause was established without experimental evidence. This was sometimes achieved by looking at the totality of evidence, using the 'Bradford Hill Guidelines', which considers factors including the strength of association, reversibility, and evidence of a plausible mechanism. In this paper we apply the Bradford Hill Guidelines to the link between social relationships and health. We conclude that having strong and supportive social relationships causes better health and longer life. Beyond establishing that social relationships are a causal factor for health, the method we used here can be applied to other areas where randomised trials are unethical or not feasible.

Can explicit suggestions about the harmfulness of EMF exposure exacerbate a nocebo response in healthy controls?

While there has been consistent evidence that symptoms reported by individuals who suffer from Idiopathic Environmental Intolerance attributed to Electromagnetic Fields (IEI-EMF) are not caused by EMF and are more closely associated with a nocebo effect, whether this response is specific to IEI-EMF sufferers and what triggers it, remains unclear. The present experiment tested whether perceived EMF exposure could elicit symptoms in healthy participants, and whether viewing an 'alarmist' video could exacerbate a nocebo response. Participants were randomly assigned to watch either an alarmist (N = 22) or control video (N = 22) before completing a series of sham and active radiofrequency (RF) EMF exposure provocation trials (2 open-label, followed by 12 randomized, double-blind, counterbalanced trials). Pre- and post-video state anxiety and risk perception, as well as belief of exposure and symptom ratings during the open-label and double-blind provocation trials, were assessed. Symptoms were higher in the open-label RF-ON than RF-OFF trial (p < .001). No difference in either symptoms (p = .183) or belief of exposure (p = .144) was observed in the double-blind trials. Participants who viewed the alarmist video had a significant increase in symptoms (p = .041), state anxiety (p < .01) and risk perception (p < .001) relative to the control group. These results reveal the crucial role of awareness and belief in the presentation of symptoms during perceived exposure to EMF, showing that healthy participants exhibit a nocebo response, and that alarmist media reports emphasizing adverse effects of EMF also contribute to a nocebo response.

Somatosensory amplification - An old construct from a new perspective

The paper reviews and summarizes the history and the development of somatosensory amplification, a construct that plays a substantial role in symptom reports. Although the association with negative affect has been supported by empirical findings, another key elements of the original concept (i.e. body hypervigilance and the tendency of focusing on mild body sensations) have never been appropriately addressed. Recent findings indicate that somatosensory amplification is connected with phenomena that do not necessarily include symptoms (e.g. modern health worries, or expectations of symptoms and medication side effects), and also with the perception of external threats. In conclusion, somatosensory amplification appears to refer to the intensification of perceived external and internal threats to the integrity of the body ("somatic threat amplification") rather than amplification of perceived or actual bodily events only. Practical implications of this new approach are also discussed.

Attribution-Based Nocebo Effects. Perceived Effects of a Placebo Pill and a Sham Magnetic Field on Cognitive Performance and Somatic Symptoms

BACKGROUND

Negative non-specific (nocebo-like) effects of medications and electromagnetic fields are often described as results of mistaken attribution.

PURPOSE

The current study aimed to find empirical evidence supporting this theory.

METHOD

Participants completed questionnaires assessing modern health worries, health anxiety, and somatosensory amplification, were assigned to one of three conditions (placebo pill with sedative information, sham magnetic field, or control), and completed a 14-min vigilance task. Changes in physiological arousal (heart rate, heart rate variability, and skin conductance) and reported symptoms were also measured. Finally, causal attributions concerning cognitive performance and reported symptoms were assessed.

RESULTS

No increase in symptom reports and physiological arousal was measured in the two intervention groups. A perceived negative effect on cognitive performance was attributed to both sham conditions, and attributions were connected to modern health worries. A proportion of reported symptoms was ascribed to the placebo pill but not to the sham magnetic field. Symptom attributions were not related to any assessed psychological variables.

CONCLUSIONS

An aroused physiological state is not necessary for the automatic causal attribution process. Negative effects attributed to medication and environmental factors can be regarded as unavoidable side effects of human cognitive-emotional functioning; they might be alleviated, but cannot be completely eradicated.

Noise sensitivity: Symptoms, health status, illness behavior and co-occurring environmental sensitivities

Epidemiological evidence on the symptomatic profile, health status and illness behavior of people with subjective sensitivity to noise is still scarce. Also, it is unknown to what extent noise sensitivity co-occurs with other environmental sensitivities such as multi-chemical sensitivity and sensitivity to electromagnetic fields (EMF). A cross-sectional study performed in the Netherlands, combining self-administered questionnaires and electronic medical records of non-specific symptoms (NSS) registered by general practitioners (GP) allowed us to explore this further. The study sample consisted of 5806 participants, drawn from 21 general practices. Among participants, 722 (12.5%) responded "absolutely agree" to the statement "I am sensitive to noise", comprising the high noise-sensitive (HNS) group. Compared to the rest of the sample, people in the HNS group reported significantly higher scores on number and duration of self-reported NSS, increased psychological distress, decreased sleep quality and general health, more negative symptom perceptions and higher prevalence of healthcare contacts, GP-registered NSS and prescriptions for antidepressants and benzodiazepines. These results remained robust after adjustment for demographic, residential and lifestyle characteristics, objectively measured nocturnal noise exposure from road-traffic and GP-registered morbidity. Co-occurrence rates with other environmental sensitivities varied between 9% and 50%. Individuals with self-declared sensitivity to noise are characterized by high prevalence of multiple NSS, poorer health status and increased illness behavior independently of noise exposure levels. Findings support the notion that different types of environmental sensitivities partly overlap.

Somatic symptoms and holistic thinking as major dimensions behind modern health worries

BACKGROUND

Modern health worries (MHWs) were related to somatic symptoms and to preference of holistic healing methods in previous studies.

PURPOSE

The study aimed to investigate the contribution of symptom-related and holism-related factors to MHWs.

METHODS

Participants (visitors of an Internet news portal; N = 16152; 64.1 % males) completed a questionnaire assessing MHWs, somatosensory amplification, somatic symptoms, positive and negative affect, spirituality, holistic health beliefs, and various aspects of health care utilization (both conventional and alternative).

RESULTS

Exploratory factor analysis with oblique rotation revealed two independent dimensions ("Somatic symptom distress" and "Holism") MHWs were involved with factor loadings of 0.294 and 0.417, respectively. The existence of two factors was supported by the results of confirmatory factor analysis. No practically significant interaction between the two factors was found in binary logistic regression analysis. Positive and negative affect, somatosensory amplification, spirituality, and holistic health beliefs were positively connected, while self-rated health status was negatively connected to MHWs even after controlling for socio-demographic and treatment-related variables.

CONCLUSIONS

Holistic thinking and symptom-related behavioral and psychological factors are independently associated with MHWs. Modern health worries can be conceptualized as symptom-related by-products of a holistic-spiritual worldview.

Review of evidence for a toxicological mechanism of idiopathic environmental intolerance

Idiopathic environmental intolerance (IEI) is a medically unexplained disorder characterised by a wide variety of unspecific symptoms in different organ systems and attributed to nontoxic concentrations of chemicals and other environmental factors that are tolerated by the majority of individuals. Both exposure to chemicals and behavioural conditioning are considered as possible contributors to the development of IEI. However, owing to the heterogeneity of the condition, it is difficult to separate the toxicological, physiological and psychological aspects of IEI. Here, we review the evidence for postulated toxicologically mediated mechanisms for IEI. Available data do not support either a classical receptor-mediated or an idiosyncratic toxicological mechanism. Furthermore, if there were convincing evidence for a psychological cause for many patients with IEI, then this would suggest that the priority for the future is the development of psychological treatments for IEI. Finally, we advocate genome wide screening of IEI patients to elucidate genotypic features of the condition.

Mass psychogenic illness: psychological predisposition and iatrogenic pseudo-vocal cord dysfunction and pseudo-reactive airways disease syndrome

A multidisciplinary team assessed five patients who alleged chronic medically unexplained multiorgan system symptoms described by idiopathic environmental intolerance allegedly triggered by exposure to solvents used in membrane roofing repair work on an office building. The event precipitated an incident of mass psychogenic illness (MPI). Treating physicians diagnosed irritant-associated vocal cord dysfunction (IVCD) and reactive airways disease syndrome (RADS) resulting from exposure. The authors conducted medical, psychological, and industrial hygiene evaluations. Air monitoring data for total volatile organic compounds obtained during the 2-day exposure period, measurements of emissions during membrane roofing repair at a similar site, mathematical modeling of air contaminant concentrations, and injection of tracer gas into the incident building revealed exposure levels well below those doses anticipated to cause clinical symptoms. There was no objective medical evidence validating symptoms. Review of the medical records indicated that the video laryngoscopy data, pulmonary function tests, and medical examinations relied upon by the treating physicians were inconsistent with published criteria for IVCD and RADS. Psychological evaluation identified defensiveness and self-serving misrepresentations of exaggerated health concerns associated with somatization and malingering. Each case had personality traits associated with at least one personality disorder. Social histories identified premorbid life events and stressors associated with distress. This is the first study to assess psychological predisposition, social interaction among the plaintiffs, and iatrogenic reinforcement of beliefs by diagnoses of pseudo-disorders associated with patient misrepresentation of exaggerated health concerns in an incident of MPI.

The airway sensory hyperreactivity syndrome

After exclusion of diverse pulmonary illnesses, the remaining explanations for chronic cough include medication with angiotensin-converting enzyme (ACE) inhibitor, gastroesophageal reflux disease (GERD), and post-nasal drip. Different clinics report shifting frequencies for both the causes of chronic cough and the success of treatment. However, after all evaluations, differential diagnosis still leaves a group of patients with unexplained cough. This unexplained cough is also known as chronic idiopathic cough (CIC), though there are widely varying opinions as to its existence. Among patients previously diagnosed with CIC, a subgroup has been identified with both upper and lower airway symptoms, including cough induced by odours and chemicals, and with increased cough sensitivity to inhaled capsaicin, which is known to stimulate the airway sensory nerves. A suggested explanation for this condition is a hyperreactivity of the sensory nerves of the entire airways, and hence the condition is known as sensory hyperreactivity (SHR). SHR affects more than 6% of the adult population in Sweden. It is a longstanding condition, and is clearly associated with significant social and psychological impacts.

Abnormalities in cognitive-emotional information processing in idiopathic environmental intolerance and somatoform disorders

Idiopathic environmental intolerance (IEI) represents a functional somatic syndrome marked by diverse bodily complaints attributed to various substances in the environment. Evidence for abnormalities in affective information processing similar to somatoform disorders (SFD) has recently been found in people with IEI. In order to further investigate these cognitive-emotional abnormalities, we compared people with IEI (n=49), SFD only (n=43), and non-somatoform controls (n=54) with respect to their performance in the extrinsic affective Simon task (EAST). This task allowed us to dissociate indicators of automatic affective associations and emotional intrusion effects of both bodily complaints and IEI-trigger words. Negative association effects toward IEI-trigger words were strongest for IEI participants. Emotional intrusion effects of symptom words were larger both in IEI and SFD than in controls. The results of enhanced negative automatic evaluations of IEI-trigger words and greater attention allocation to symptom words support cognitive models of IEI.

Modern health worries and idiopathic environmental intolerance

OBJECTIVE

We conducted two studies to test whether modern health worries (MHWs) were associated with central features of a condition called idiopathic environmental intolerance (IEI) and medical care utilization.

METHODS

In Study 1, 474 Internet users completed an Internet-based questionnaire that assessed MHWs, IEI features, and medical care utilization. In Study 2, the diagnostic specificity of MHWs was investigated by comparing the level of MHWs of three diagnostic groups: 46 people with IEI, 38 people with somatoform disorder but without IEI, and 46 people with neither IEI nor somatoform disorder.

RESULTS

The good psychometric properties of the MHW scale were confirmed. MHWs were related to various features of IEI, and people who met IEI case criteria showed consistently higher levels of MHWs compared with people without IEI. The link between MHWs and number of doctor visits was mediated by perceived IEI complaints. In Study 2, the MHW scale effectively discriminated the IEI group from the non-IEI groups.

CONCLUSIONS

These results suggest that MHWs may contribute to the development of IEI. However, only prospective longitudinal studies will enable us to determine the predictive importance of MHWs for later development of IEI.

The German Multicentre Study on Multiple Chemical Sensitivity (MCS)

In this multicentre study on multiple chemical sensitivity (MCS) 291 consecutive environmental medicine (EM) outpatients were examined in several environmental medicine outpatient centres/units throughout Germany in 2000/2003. Of the EM outpatients, 89 were male (30.6%) and 202 were female (69.4%), aged 22-80 (mean 48 years, S.D.=12 years). The sample was representative for university-based environmental outpatient departments and represented a cross-sectional study design with an integrated clinical-based case-control comparison (MCS vs. non-MCS). Three classifications of MCS were used: self-reported MCS (sMCS), clinically diagnosed MCS (cMCS), and formalised computer-assisted MCS with two variants (f1MCS, f2MCS). Data were collected by means of an environmental medicine questionnaire, psychosocial questionnaires, the German version of the Composite International Diagnostic Interview (CIDI), and a medical baseline documentation, as well as special examinations in partial projects on olfaction and genetic susceptibility markers. The hypothesis guided evaluation of the project showed that the patients' heterogenic health complaints did not indicate a characteristic set of symptoms for MCS. No systematic connection could be observed between complaints and the triggers implicated, nor was there any evidence for a genetic predisposition, or obvious disturbances of the olfactory system. The standardised psychiatric diagnostics applying CIDI demonstrated that the EM patients in general and the subgroup with MCS in particular suffered more often from mental disorders compared to an age and gender matched sample of the general population and that in most patients these disorders commenced many years before environment-related health complaints. Our results do not support the assumption of a toxicogenic-somatic basis of the MCS phenomenon. In contrast, numerous indicators for the relevance of behavioural accentuations, psychic alterations or psychosomatic impairments were found in the group of EM-outpatients with subjective "environmental illness".

Olfactory receptor gene polymorphisms and nonallergic vasomotor rhinitis

We sought a genotype-phenotype association: between single-nucleotide polymorphisms (SNPs) in olfactory receptor (OR) genes from the two largest OR gene clusters and odor-triggered nonallergic vasomotor rhinitis (nVMR). In the initial pedigree screen, using transmission disequilibrium test (TDT) analysis, six SNPs showed "significant" p-values between 0.0449 and 0.0043. In a second case-control population, the previously identified six SNPs did not re-emerge, whereas four new SNPs showed p-values between 0.0490 and 0.0001. Combining both studies, none of the SNPs in the TDT analysis survived the Bonferroni correction. In the population study, one SNP showed an empirical p-value of 0.0066 by shuffling cases and controls with 10(5) replicates; however, the p-value for this SNP was 0.83 in the pedigree study. This study emphasizes that underpowered studies having p-values between < 0.05 and 0.0001 should be regarded as inconclusive and require further replication before concluding the study is "informative." However, we believe that our hypothesis that an association between OR genotypes and the nVMR phenotype remains feasible. Future studies using either a genomewide association study of all OR gene-pseudogene regions throughout the genome--at the current recommended density of 2.5 to 5 kb per tag SNP--or studies incorporating microarray analyses of the entire "OR genome" in well-characterized nVMR patients are required.

A two-week monitoring of self-reported arousal, worry and attribution among persons with annoyance attributed to electrical equipment and smells

Non-patients attributing annoyance to either smells (smell annoyed; SA, n= 29) or electrical equipment (electrically annoyed; EA, n= 17), or both (generally annoyed; GA, n= 38), were monitored for 2 weeks through daily self-ratings of arousal (stress), sleep disturbances, health complaints, worry about hypersensitivity reactions, avoidance behaviors, and attributions of health complaints to electrical equipment and smells. In parallel, a demographically matched reference group was followed (n= 56). GA persons reported higher arousal (stress), more subjective health complaints, and more sleep disturbances than the other groups. About 60% in the GA and EA groups reported intentional avoidance behavior, compared to 31% in the SA group and 2% of the referents. Worry and attribution to environmental factors was also more frequent among GA persons than in the other groups. Thus, even at sub-clinical levels, environmental annoyance generalized to several triggers seems to be associated with behaviors commonly observed among patients with idiopathic environmental intolerance.

Evidence for a specific link between the personality trait of absorption and idiopathic environmental intolerance

Absorption as a personality trait refers to the predisposition to get deeply immersed in sensory (e.g., smells, sounds, pictures) or mystical experiences, that is, to experience altered states of consciousness. Absorption is markedly related to constructs openness to experiences, hypnotic suggestibility, imagination, and dissociation. Although absorption was hypothesized to be a risk factor for medically unexplained symptoms (MUS), the construct has yet not been investigated in individually suffering from idiopathic environmental intolerance (IEI), formerly better known as multiple chemical sensitivity (MCS). IEI is a complex condition marked by MUS, which patients attribute to various chemical substances that are typically detectable by their odor (e.g., exhaust emissions, cigarette smoke). The current study investigated whether IEI was related to the personality trait of absorption. In a longitudinal study, 54 subjects with IEI were compared to 44 subjects with a somatoform disorder (SFD), but without IEI, and 54 subjects with neither SFD nor IEI (control group, CG). Self-report measures of somatic symptoms, severity of IEI, and level of absorption were collected both at a first examination and 32 mo later. On both assessments, subjects with IEI and individuals with SFD reported similar highly elevated levels of MUS, compared to CG. In contrast to SFD, IEI was specifically related to elevated absorption scores. IEI was specifically associated with a tendency to experience self-altering states of consciousness. Since absorption is related to both openness to unusual experiences and elevated imaginative involvement, absorption might contribute to IEI via two routes by (1) enhancing the susceptibility for IEI-specific convictions and (2) fostering classical conditioning processes of MUS via enhanced cognitive-imaginative representations of assumed IEI triggers.

Moderne Gesundheitssorgen und ihre Beziehung zu umweltbezogenen Beschwerden

Zusammenfassung. Theoretischer Hintergrund: Nach Petrie und Wessely (2002) bedeuten neue Technologien (z.B. Mobiltelefone und gentechnologisch veränderte Nahrungsmittel) neue Gesundheitssorgen und -beschwerden. Diese modernen Gesundheitssorgen können mittels Fragebogen standardisiert erfasst werden. Fragestellung: Es wurden die Faktorenstruktur, Reliabilität und Validität einer deutschen Übersetzung der Modern Health Worries (MHW) Scale sowie deren Beziehung zu einem funktionellen umweltbezogenen Syndrom, der Idiopathischen Umweltintoleranz (IUI), untersucht. Methode: 757 Studenten einer deutschen Universität füllten Fragebögen zur Erfassung von MHW, IUI, Krankheitsangst, Depressivität und multiplen körperlichen Beschwerden aus. Ergebnisse: Die vier Subskalen der MHW-Skala - Umweltgifte, Umweltverschmutzung, belastete Nahrungsmittel und elektrische Strahlung - konnten faktorenanalytisch bestätigt werden. Die interne Konsistenz (Cronbach’s α) der Subkalen erreichte Werte zwischen .77 und .89. MHW, negativer Affekt und Somatisierungsneigung trugen als unabhängige Prädiktoren jeweils signifikant zur Vorhersage des IUI-Beschwerdeniveaus bei. Schlussfolgerungen: Die deutsche Version der MHW-Skala kann als Messinstrument zur Verwendung für wissenschaftliche Zwecke empfohlen werden. Die Implikationen der Befunde für ein psychogenes Modell der IUI werden diskutiert.

Psychological predictors of short- and medium term outcome in individuals with idiopathic environmental intolerance (IEI) and individuals with somatoform disorders

Idiopathic environmental intolerance (IEI), also known as multiple chemical sensitivity (MCS), is defined as a chronic polysymptomatic condition that cannot be explained by an organic disease. Previous studies suggest that IEI may be a variant of somatoform disorders (SFD), because both disorders overlap with respect to symptoms and psychological features of somatization. However, little is known about the short- and medium-term outcome of IEI and psychological outcome predictors. Two clinical groups (IEI and SFD) and a comparison group (CG) were followed through 32 mo to assess both the outcome, and the extent to which trait anxiety and somatic symptom attribution (assessed at first examination) predict outcome presented 12 and 32 mo later. Outcome measures were the number of self-reported IEI symptoms, IEI triggers, IEI-associated functional impairments, and the number of somatoform symptoms. In addition, the course of the 2 syndromes over the 32-mo follow-up period was investigated with standardized screening scales. The 3 diagnostic groups consisted of 46 subjects with IEI, 38 subjects with SFD but without IEI, and 46 subjects (CG) with neither IEI nor SFD. Syndrome stability was high over the 32-mo follow-up period, and at both follow-ups IEI and non-IEI subjects differed on all IEI outcome measures (symptoms, triggers, functional impairments). Both trait anxiety and somatic attribution (the tendency to attribute common somatic complaints to an illness) predicted outcome. In addition, somatic attribution was found to partially mediate the effect of trait anxiety on outcome in the IEI group. In conclusion, these results suggest that IEI is a chronic and disabling condition and that trait anxiety contributes to the maintenance of the disorder via somatic attributions.

Trauma experience in individuals with idiopathic environmental intolerance and individuals with somatoform disorders

OBJECTIVE

Results from previous studies suggest that past trauma experience increases the risk for medically unexplained somatic symptoms and somatoform disorders (SFD). This cross-sectional study examined the link between various lifetime traumas, idiopathic environmental intolerance (IEI), and SFD.

METHODS

Two clinical groups of 54 subjects with IEI and 44 subjects with SFD were compared to 54 subjects (comparison group, CG) free from both IEI and SFD regarding self-reported traumas. The subjects were mainly recruited via advertisements in local newspapers. From 970 individuals screened for IEI and multiple somatic symptoms, 152 were included through a two-step selection procedure consisting of screening questionnaires, a medical examination, and structured interviews for IEI and mental disorders.

RESULTS

In all three groups at least one potential traumatic event was reported rather frequently (CG: 70%; IEI: 82%; SFD: 73%). But contrary to our expectation, significant group differences were neither found in regard to the proportion of subjects with any trauma, nor traumas fulfilling DSM-IV criteria (CG: 41%; IEI: 48%; SFD: 59%), nor multiple traumas (CG: 43%, IEI: 56%, SFD: 39%). Only two trauma categories were endorsed more frequently by the two clinical groups than by the CG: the unspecified 'other' category (IEI, SFD>CG) and 'life-threatening illness' (IEI>CG).

CONCLUSION

No clear evidence was found for increased rates of trauma experience in IEI and SFD. However, the results of this exploratory study should be considered as preliminary. Comparing larger IEI and SFD groups with a representative population-based sample may yield different results.

Psychologische Korrelate des Multiple Chemical Sensitivity (MCS)

Zusammenfassung. Theoretischer Hintergrund: Multiple Chemische Sensitivität (MCS) ist ein Syndrom mit organisch unerklärbaren Beschwerden, die von den Betroffenen auf niedrig dosierte Umweltschadstoffe attribuiert werden. Eine Risikogruppe für MCS stellen Probanden (Pbn) mit selbstberichteter Chemischer Sensitivität (CS) dar. Fragestellung: Sind eher toxikogene oder eher psychogene Faktoren für den Bericht von MCS-Beschwerden entscheidend? Methode: Fragebogenuntersuchung an 309 Studierenden, die sich in einem mit Polychlorierten Biphenylen (PCB) belasteten Universitätsgebäude aufhielten; Querschnittstudie. Ergebnisse: Während Expositionsdauer und MCS-Syndrom nicht korrelierten, lieferten psychologische Variablen (umweltbezogene Gefährdungskognitionen, Krankheitsangst, habituelle Sorgen und Absorption) hingegen einen signifikanten Beitrag zur Vorhersage des MCS-Syndroms. Nur Pbn mit CS, aber nicht jene ohne CS, berichteten nach Aktivierung eines “Schadstoffbelastungs-Schemas“ vermehrt MCS-Beschwerden. Schlussfolgerungen: Nach den Ergebnissen dieser Querschnittsuntersuchung und anderer Studien scheinen kognitive und andere psychologische Faktoren eine bedeutsame Rolle bei der Entstehung und Aufrechtung dieses Syndroms zu spielen.

MMPI-2 validity, clinical and content scales, and the Fake Bad Scale for personal injury litigants claiming idiopathic environmental intolerance

BACKGROUND

Idiopathic environmental intolerance (IEI) is a descriptor for nonspecific complaints that are attributed to environmental exposure.

METHODS

The Minnesota Multiphasic Personality Inventory 2 (MMPI-2) was administered to 50 female and 20 male personal injury litigants alleging IEI.

RESULTS

The validity scales indicated no overreporting of psychopathology. Half of the cases had elevated scores on validity scales suggesting defensiveness, and a large number had elevations on Fake Bad Scale (FBS) suggesting overreporting of unauthenticated symptoms. The average T-score profile for females was defined by the two-point code type 3-1 (Hysteria-Hypochondriasis), and the average T-score profile for males was defined by the three-point code type 3-1-2 (Hysteria, Hypochondriasis-Depression). On the content scales, Health Concerns (HEA) scale was significantly elevated.

CONCLUSION

Idiopathic environmental intolerance litigants (a) are more defensive about expressing psychopathology, (b) express distress through somatization, (c) use a self-serving misrepresentation of exaggerated health concerns, and (d) may exaggerate unauthenticated symptoms suggesting malingering.

Psychiatric morbidity and toxic burden in patients with environmental illness: a controlled study

OBJECTIVE

Patients with environmental illness experience a large number of psychological symptoms. The nature of these symptoms and their pathogenesis (toxicogenic versus psychogenic) is controversial. The objective was to (1) characterize the nature of the psychological symptoms according to well-established diagnostic criteria, and (2) to investigate the association between toxicological factors and psychological symptoms.

METHODS

Toxic burden, somatic morbidity, and psychiatric morbidity were assessed in 309 outpatients with environmental illness and 59 semiconductor industry workers matched for age and gender. Psychiatric disorders were assessed by a structured psychiatric interview (SCID), and distress was assessed by the Symptom-Checklist-90-Revised (SCL-90-R). Routine and specific laboratory tests in blood and urine samples were used to assess chemical exposures.

RESULTS

Overall psychiatric morbidity was significantly higher in patients than in controls according to SCID (75% versus 24%). Somatoform, mood, and anxiety disorders were significantly more frequent in patients with environmental illness. They also revealed marked stress on the SCL-90-R somatization subscale and scored significantly higher than controls on most of the other subscales. Industry workers from the control group tended to have higher urine metal concentrations than environmental illness patients and similar concentrations of solvents in blood.

CONCLUSION

Our data extend previous findings of high psychiatric morbidity in patients with environmental illness. They do not support the notion of a direct causal link between chemical exposure and the psychological symptoms.

Selective attention, memory bias, and symptom perception in idiopathic environmental intolerance and somatoform disorders

Idiopathic environmental intolerance (IEI) refers to a polysymptomatic condition, similar to somatoform disorders. Various processes seem to contribute to its yet unknown etiology. Attention and memory for somatic symptom and IEI-trigger words was compared among participants with IEI (n = 54), somatoform disorders (SFD; n = 44) and control participants (n = 54). Groups did not differ in a dot-probe task. However, in an emotional Stroop task, attention was biased in IEI and SFD groups toward symptom words but not toward IEI-trigger words. Only the IEI group rated trigger words as more unpleasant and more arousing, and participants remembered them better in a recognition task. These implicit and explicit cognitive abnormalities in IEI and SFD may maintain processes of somatosensory amplification.

Chemical sensitivity and the work place environment: research needs

Large numbers of studies of multiple chemical sensitivity (MCS) have been performed, particularly in clinical settings. Epidemiological studies in the area are scarce, and this is also the case for cacosmia. Very few have studied the work place conditions for the MCS patient at the onset of symptoms, neither the chemical exposure nor psychosocial conditions. This type of research is of interest to understand the development of the syndrome and to suggest preventive actions in the work places.

Idiopathic Environmental Intolerance

Toxicogenic and psychogenic theories have been proposed to explain idiopathic environmental intolerance (IEI). Part 2 of this article is an evidence-based causality analysis of the psychogenic theory using an extended version of Bradford Hill's criteria. The psychogenic theory meets all of the criteria directly or indirectly and is characterised by a progressive research programme including double-blind, placebo-controlled provocation challenge studies. We conclude that IEI is a belief characterised by an overvalued idea of toxic attribution of symptoms and disability, fulfilling criteria for a somatoform disorder and a functional somatic syndrome. A neurobiological diathesis similar to anxiety, specifically panic disorder, is a neurobiologically plausible mechanism to explain triggered reactions to ambient doses of environmental agents, real or perceived. In addition, there is a cognitively mediated fear response mechanism characterised by vigilance for perceived exposures and bodily sensations that are subsequently amplified in the process of learned sensitivity. Implications for the assessment and treatment of patients are presented.