Psychological features of subjects with idiopathic environmental intolerance

doi:10.1016/S0022-3999(01)00250-1

Journal of Psychosomatic Research

Volume 51, Issue 3, September 2001, Pages 537-541

https://doi.org/10.1016/S0022-3999(01)00250-1 Get rights and content

Abstract

Objectives: Idiopathic environmental intolerance (IEI) is associated with unexplained symptoms attributed to nonnoxious levels of environmental substances. Clinically, some of the symptoms of IEI overlap with those of panic disorder (PD). We have recently reported a link between IEI and panic responses to a single inhalation of 35% carbon dioxide (CO₂), a reliable panic induction challenge. This study assessed depression, stress, anxiety, and agoraphobic symptoms among IEI subjects from our previous study versus healthy controls. Methods: Thirty-six IEI and 37 control subjects with no preexisting psychiatric history were compared on self-report psychological questionnaires. Results: IEI subjects scored significantly higher than controls on the Agoraphobic Cognitions Questionnaire (ACQ), Depression Anxiety Stress Scales (DASS), and Mobility Inventory for Agoraphobia (MI) (Student's t, P<.05). Conclusions: IEI subjects represent a group with morbidity significantly higher than a control population but less than what would be expected for a clinical psychiatric population.

Introduction

Idiopathic environmental intolerance (IEI), also known as multiple chemical sensitivity, is a controversial description for which there is a lack of consensual findings with respect to its prevalence, diagnostic criteria, etiology, and therapeutic strategies. There is substantial heterogeneity in exposure, illness history, and presentation among persons with IEI, hampering efforts towards a universally accepted clinical definition [1], [2], [3], [4].

On average, IEI patients seen clinically are between 40 and 50 years of age with approximately four times as many women affected as men. Furthermore, no single chemical or psychosocial situation can be defined as being more prevalent than any other for onset of symptoms [5]. The most frequent symptoms include anxiety, lightheadedness, impaired mentation, poor coordination, breathlessness (without wheezing), tremor, and abdominal discomfort [6]. IEI patients attribute these symptoms to various environmental chemicals [6].

A number of hypotheses have been generated regarding the etiology of IEI. A central question has been whether individuals characterized with IEI are suffering from a toxic or allergic disorder or whether psychological factors cause at least some to develop physical symptoms, which they attribute to allergy or toxic mechanisms. Since allergy has not been clearly demonstrated, and current toxicological paradigms for exposure–symptom relationships do not readily accommodate IEI, psychogenic theories have also been the focus of a number of investigations [2], [3].

There are a number of findings of increased psychiatric morbidity among IEI patients [4], [7], [8], [9], [10]. Simon et al. [4] reported a greater prevalence of current anxiety or depressive disorders among patients with IEI compared to controls with chronic musculoskeletal injuries. Black et al. [10] found a significantly higher lifetime prevalence of major depression, mood disorders, anxiety disorders, and somatization disorder among patients with environmental illness compared to controls. Fiedler et al. [9] compared psychiatric morbidity in patients with IEI, chronic fatigue syndrome (CFS), and healthy controls. Current diagnoses of a major depressive episode were significantly higher among IEI and CFS patients than in controls. Evidence in IEI patients [11], [12] also suggest that panic responses may play a role in their symptoms. Leznoff [11] found that in 11 of 15 IEI patients challenged with their trigger substances, there was an objective measurement of hypocarbia to account for symptoms, evidence of an anxiety reaction. In a pilot study, Binkley and Kutcher [7] reported that all five IEI patients experienced a symptomatic panic response following intravenous sodium lactate infusion, a challenge that has been shown to trigger panic attacks in patients with panic disorder (PD) [13]. Independent psychiatric assessment resulted in the diagnosis of PD on the basis of DSM-III-R criteria in each of the five patients [7]. A study by our group [14] found that panic was elicited in significantly more IEI subjects than controls following a single-breath inhalation of 35% carbon dioxide (CO₂), a reliable trigger of experimental panic among patients with PD. In addition, IEI subjects scored significantly higher on the Anxiety Sensitivity Index (ASI) [15] compared to controls. The ASI measures the extent to which people are fearful of the physical sensations that are associated with arousal and anxiety. People with PD have been found to have higher ASI scores than people with other anxiety disorders and normal controls [16]. Therefore, evidence supports the possibility that panic symptomatology may be heightened in people with IEI.

The purpose of the current report was to assess the role of PD and other psychopathology in IEI using self-report measures of anxiety, depression, stress, and agoraphobia in a case-control study. It was hypothesized that on self-report standardized measures of anxiety sensitivity, anxiety, depression, stress, and agoraphobia, IEI subjects would score significantly higher than controls. The extent to which psychological responses play a role in IEI may suggest a rationale for psychotherapy or psychopharmacologic intervention studies in patients with IEI.

Section snippets

Method

Thirty-six subjects with symptoms to suggest IEI and 37 normal controls were recruited from our study of panic responses to a single-breath inhalation of 35% CO₂ as previously described [14]. Eighteen subjects with IEI were recruited from either the practices of the study allergists or an earlier study of environmental illness [17]. The remaining 18 IEI subjects were recruited by advertisement. Individuals were screened using criteria obtained from Simon et al. [4] who conducted a

Subjects

One hundred and four IEI subjects were contacted. Thirty-three did not meet our IEI criteria. Of the remaining 71 candidate IEI subjects, 32 were ruled out for various reasons. Fourteen of the 32 subjects (44%) were excluded because they were currently in treatment for an anxiety disorder, 5 (16%) reported suffering from migraines, 11 (35%) declined to participate, 1 (3%) reported suffering from asthma, and 1 (3%) could not schedule an appropriate visit time. Of the remaining 39 subjects who

Discussion

The previous reports of psychopathology [4], [7], [8], [9], [10] and the overlap in symptoms between IEI and PD patients prompted us to compare the responses of IEI subjects to controls on self-reported measures of anxiety, stress, depression, and agoraphobic symptoms. We postulated IEI subjects would score similarly to PD patients on these psychological measures.

IEI subjects scored significantly higher than controls on standard self-report questionnaires measuring anxiety, stress, agoraphobia,

Acknowledgements

We wish to thank Justina Greene for statistical assistance, Irvin Broder for helpful suggestions, and Pat Brown, for administrative assistance. This study was funded in part by a grant from the St. Michael's Hospital Research Foundation.

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Cited by (22)

Multiple Chemical Sensitivity/Idiopathic Environmental Intolerance: A Practical Approach to Diagnosis and Management
2023, Journal of Allergy and Clinical Immunology: In Practice
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.
Differences in psychological and somatic symptom cluster score profiles between subjects with Idiopathic environmental intolerance, major depression and schizophrenia
2017, Psychiatry Research
Citation Excerpt :
Bailer et al. (2005) concluded that the two groups cannot be distinguished on the phenomenological level except with regard to different styles of symptom attribution. Since enhanced state and trait anxiety, physical concerns, and dysfunctional body-related cognitions are commonly reported in IEI patients, several authors assumed that IEI is a variant of anxiety disorders (Poonai et al., 2001; Tonori et al., 2001; Bailer et al., 2005; Papo et al., 2006;). The similarity between IEI and anxiety disorders is also underlined by suggestions that IEI shares an underlying neurobiological diathesis with panic disorder (Binkley and Kutcher, 1997; Poonai et al., 2000).
Idiopathic Environmental Intolerance (IEI) has been associated with psychogenic factors and an increased number of comorbid psychiatric disorders such as depression and anxiety disorder. The purpose of the current study was to examine a possible overlap of psychological and somatic symptoms between subjects with IEI and patients with major depression and schizophrenia as well as to specify characteristic differences. The different symptom clusters included symptoms of chemical intolerance, neurotoxicity and psychological distress as well as measurements of mental health such as anxiety, depression, somatoform symptoms, and schizophrenia-specific disturbances in cognitive domains. IEI patients reported higher overall levels in physical symptoms such as chemical intolerance, neurotoxicity and somatic symptoms not attributable to an organic cause. Schizophrenia patients showed higher overall levels in self-experienced disturbances in several schizophrenia-specific cognitive domains, whereas general psychological distress, anxiety and depression were rated highest by patients with major depression. Importantly, the groups markedly differed in the shapes of profiles of various symptom clusters. Our results provide evidence that IEI patients can be distinguished on the phenomenological level from patients with major depression or schizophrenia, and that distinct domains of psychological and somatic symptoms are particularly problematic in specific diagnostic groups.
Assessment of somatic complaints in environmental health
2009, International Journal of Hygiene and Environmental Health
In patients attributing their health complaints to environmental factors (EnvPat) evidence based medical diagnostics usually do not confirm environmental and somatic causes of symptoms. Many symptoms remain unexplained. Aim of the study was the systematic assessment of medically unexplained physical symptoms (MUPS) in EnvPat and comparison to symptom rates reported by subjects of an environmental study exposed to environmental odors (EnvExp). This specific exposure was chosen, as odors are associated by an unclear mechanism with physical symptoms. By this we aimed to enlighten the open question as to likeliness that MUPS of EnvPat are caused by hitherto unrevealed environmental exposures or result from somatization. MUPS were measured with SOMS-2 in EnvPat n=92, patients presenting in a university environmental outpatients clinic, and different study groups exposed to environmental odors (EnvExp). These were: (1) subjects exposed to annoying odors and medically relevant concentrations of bioaerosols, such as airborne microorganisms (EnvExp-1, n=74), and (2) subjects exposed to odors alone (EnvExp-2, n=282) as well as unexposed controls (Controls, n=235). Logistic regression and analysis of variance were applied to analyze rates of single complaints and the sum index of complaints (SOMS-CoIx). In EnvPat rates of MUPS were highest – significant (p<0.05) adjusted OR in 23 of 25 MUPS compared to controls – and highest SOMS-CoIx (mean 15.3 (S.D. ±9.3). Rates of MUPS were lower in environmentally exposed subjects with difference in the two strata: while EnvExp-1 differed in several complaints, i.e., nausea and SOMS-CoIx (mean 7.2, S.D. ±6.9) from controls (p<0.05), EnvExp-2 (SOMS-CoIx mean 4.8, S.D. ±5.2) showed relevant differences only in two single complaints and not in the SOMS-CoIx from controls, SOMS-CoIx mean 3.9, S.D. ±5.0. This remained when adjusting for age, gender, and school education. Rates of MUPS in environmental patients were clearly higher than in subjects with actual environmental exposure, making it unlikely that their symptoms are due to undetected environmental factors. MUPS of EnvPat show similarities to psychosomatic patients. In the environmental survey symptom assessment by SOMS-2 was sensitive to different environmental scenarios, i.e., higher rates of physical complaints were only found in subjects with hazardous residential bioaerosols pollution as well as an annoying odor exposure and interestingly not in subjects exposed to annoying odors alone. This underlines that questionnaire data of somatic complaints need to be interpreted on the basis of exposure assessment in order to unjustly attribute health complaints to annoyance.
The German Multicentre Study on Multiple Chemical Sensitivity (MCS)
2008, International Journal of Hygiene and Environmental Health
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”.
Subgrouping outpatients of an environmental medicine unit using SCL-90-R and cluster analysis
2007, International Journal of Hygiene and Environmental Health
Citation Excerpt :
Roughly spoken are there two sides: proponents of clinical ecology consider exposure to environmental factors like chemicals as the main or even sole cause whereas representatives of scientific medicine rather prefer psychosomatic models (Eis, 1998/99). None of these hypotheses is unambiguously proven, but it is generally accepted now that environmental ‘syndromes’ have a greater or lesser psychosomatic dimension (Eis et al., 2005a; Henningsen and Priebe, 2003; Huss et al., 2004; Fishbein, 1996; Papo et al., 2004; Poonai et al., 2001; Staudenmayer, 1998; Wiesmüller et al., 2003). Objective physical findings and consistent laboratory results are most typically not existent (Labarge and McCaffrey, 2000).
Between 1999 and 2003 all consecutive outpatients of the environmental medicine unit of the Charité hospital in Berlin were invited to participate in a study on environmentally related disorders. One hundred and sixty-nine of the patients completed a psychosocial questionnaire which comprised SCL-90-R and 14 other tests. When compaired with clinical controls, SCL-90-R mean scores of the environmental patients (EP) were found to lie in between those of inpatients of a psychosomatic clinic and melanoma aftercare patients; but they were, with exception of the somatisation dimension, much closer to the latter. Application of the TwoStep Cluster™ component of SPSS resulted in three subgroups with high, moderate and low scores which were significantly different ( $p < 0.001$ ) although separation was incomplete (87% correct identification; cross-validated discriminant analysis). With all subgroups, scores for somatisation, depression and obsessive compulsion were highest and those for phobic anxiety and psychoticism were lowest. SCL-90-R scores correlated well with results of the Freiburg Personality Inventory, Whiteley Index of hypochondriasis, the short form health questionnaire (SF-36), and the Composite International Diagnostic Interview (CIDI). Hierarchical grouping (average linkage between groups), performed with involvement of SCL-90-R data from literature, resulted in a dendrogram with three distinct groups and three outliers. EP with low SCL-90-R scores were assigned to a group which comprised also general populations (USA, Germany), allergy patients, and melanoma controls. Those with moderate SCL-90-R scores were placed in a group together with chronic pain patients, and 26 ‘environmentally ill’ subjects. The third subgroup of EP formed a cluster with our psychosomatic controls, psychosomatic patients from another study, depressed people, and patients undergoing psychotherapy. The three outliers of the dendrogram, however, were SCL-90-R profiles obtained from persons with toxic waste exposure, neurotoxic workplace exposure or with solvent-induced chronic toxic encephalopathy.
Breathing and heart rate during experimental solvent exposure of young adults with self-reported multiple chemical sensitivity (sMCS)
2003, NeuroToxicology
This paper deals with the assumption that young adults with self-reported multiple chemical sensitivity (sMCS) show a heightened sensitivity of autonomic functions during experimental solvent exposure. Male sMCS-subjects were selected (out of n=274) on the base of a German questionnaire on chemical and environmental sensitivity (CGES). Two independent experiments were carried out, each with 12 sMCS-subjects and 12 age-matched control-subjects. In experiment I two concentrations of the solvents ethyl benzene (10 and 98 ppm) and 2-butanone (10 and 189 ppm) were used. Experiment II investigated 2-propanol (35 and 190 ppm) and 1-octanol (0.1 and 6.4 ppm). The low concentrations correspond nearly to the olfactory thresholds while the high concentrations correspond to the German occupational threshold limit values (MAC). The exposure duration under each condition was 4 h. The sequence of the four exposure conditions was random including intervals of at least 2 days without exposure. During the exposure physiological changes of breathing rate and heart rate were recorded. Two 30 min intervals with a sedentary position of the subjects at the beginning and end of exposure were chosen for analyses. Neither in experiment I nor in experiment II significant specific reactions to the type or level of the exposures were found. The autonomic functions in both experiments revealed alterations within the exposure sessions. The heart rate in experiment II and the breathing rate in both experiments decreased significantly during the analyzed 30 min intervals. Furthermore, in both experiments the heart rates decreased significantly from beginning to end of exposure. Only in experiment I the mean breathing rate of sMCS-subjects was generally higher compared to the control-subjects. Regarding the assumption of a heightened sensitivity of sMCS-subjects the two experiments yielded controversial results. Thus, the hypothesis of stronger responses of autonomic functions of sMCS-subjects provoked by various exposure scenarios remains open.

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Psychological features of subjects with idiopathic environmental intolerance

Abstract

Introduction

Section snippets

Method

Subjects

Discussion

Acknowledgements

J Allergy Clin Immunol

J Allergy Clin Immunol

J Allergy Clin Immunol

Behav Res Ther

J Anxiety Disord

Behav Res Ther

Behav Res Ther

Behav Res Ther

Measuring chemical sensitivity prevalence: a questionnaire for population studies

Am J Public Health

Environmental illness: a clinical review of 50 cases

Arch Intern Med

The relationship of mental disorders and idiopathic environmental intolerance

Occup Med