Study of Cognitive and Behavioural Biases in People With Idiopathic Environmental Intolerance (IEI) Versus Healthy Controls

NCT06800976 | Not Yet Recruiting

• 1 other identifier: C24-26
• Study Type: observational
• Target: 69
• Locations: 1 country
• Sites: 1

Brief Summary

Symptoms that patients attribute to the environment when no environmental cause can be identified are known as "idiopathic environmental intolerance" (IEI). IEI is often associated with a major psychological and socio-professional impact. Specific diagnostic tools and evidence-based treatment programs are still lacking. As a result, IEI patients often feel left behind by physicians and public health policies. A number of environmental agents are singled out by IEI sufferers, including chemicals (cleaning products, tobacco smoke), electromagnetic fields generated by cell phones and base stations, air conditioning and infrasound emitted by wind turbines. Patients hold one or more of these environmental agents responsible for a very wide range of chronic, non-specific physical symptoms such as diffuse pain, fatigue, dizziness, dyspnoea, hot flushes, nausea, tinnitus or palpitations, but also cognitive symptoms such as loss of memory or concentration. However, the medical examination of IEI patients shows no evidence of bodily dysfunction. Furthermore, numerous exposure studies have shown that environmental agents did not alter the biological parameters of IEI patients, that patients could not reliably distinguish between real and fictitious exposures, and that they only presented symptoms when they thought the exposure was real, whether this was true or not. This suggests that IEI symptoms can be considered "functional", resulting from an alteration in the way the body is felt rather than from injury to the body itself. Recently, several authors including Lemogne and Pitron have proposed a cognitive model of body awareness and more specifically of functional physical symptoms.This model is part of a Bayesian understanding of brain function, which is increasingly seen as a process underlying all perceptual experiences.From this perspective, bodily experiences are the result of probabilistic calculations Two sources of information are integrated, weighted by their reliability (accuracy) with regard to the current context: the body's sensory signals on the one hand (i.e. peripheral nerve inputs) and "priors" about the body on the other (i.e. pre-existing information from previous bodily experiences, beliefs about the body, emotions, etc.). In functional physical symptoms, it has been suggested that priors override the body's sensory signals, thus skewing bodily perception.This would be the consequence of an imbalance between low-precision sensory signals on the one hand, and high-precision priors on the other. In line with this model, Van den Bergh and Witthöft have proposed an understanding of IEI as arising from a nocebo effect.Here, we propose a research project with patients suffering from IEI to test and validate this Bayesian theoretical model of IEI, the main study C22-19, BELIEFS which is currently recruiting. This ancillary study, C24-26 BELIEFS-VS, enables us to include a population of healthy volunteers whom we will compare with the IEI patients in the main C22-19 BELIEFS study.

Conditions

Healthy Volunteers; Idiopathic Environmental Intolerance

Keywords

predictive processing; Mechanisms; symptoms associated with environmental factors; negative affect

Outcome Measures

Primary Outcomes (2)

• Performance on the Belief Updating Task

  (Single assessment)

• Performance on the Affective Picture Paradigm

  (Single assessment)

Secondary Outcomes (10)

• The Somatic Symptom Disorder - B Criteria Scale

  (Single Assessment)

• Symptom Interpretation Questionnaire

  (Single Assessment)

• Modern Health Worries Scale short (12-item) version

  (Single Assessment)

• Climate Change Anxiety Scale

  (Single Assessment)

• Hospital Anxiety and Depression scale

  (Single Assessment)

Study Arms (1)

Healthy

Healthy participants with no idiopathic environmental intolerance

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

We are recruiting healthy participants that will be age- and gender-matched to participants in the BELIEFS study, who live with idiopathic environmental intolerances.

You may qualify if:

• years of age or older; not suffering from an idiopathic environmental intolerance; informed consent is given.

You may not qualify if:

• Suffering from a current psychiatric or neurological condition
• not being fluent in spoken and written French
• being imprisoned/jailed
• being hospitalized
• Persons of legal age who are subject to a legal protection measure (e.g. conservatorship, guardianship), persons of legal age who are unable to express their consent and who are not subject to a protection measure.
• being pregnant or breast-feeding
• Translated with DeepL.com (free version)

Sponsors & Collaborators

• Institut National de la Santé Et de la Recherche Médicale, France: lead

Study Sites (1)

Unité de pathologies professionnelles et environnementales, Hôtel-Dieu

Paris, Île-de-France Region, 75004, France

Location

MeSH Terms

Conditions

Multiple Chemical Sensitivity

Condition Hierarchy (Ancestors)

Environmental Illness; Hypersensitivity; Immune System Diseases; Disorders of Environmental Origin

Study Officials

• Cédric Lemogne, Dr.

  APHP Hôtel-Dieu

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Victor Pitron, Dr.

CONTACT

+33142348608; victor.pitron@aphp.fr

Tara M Petzke, Dr.

CONTACT

tara.petzke@inserm.fr

Study Design

• Study Type: observational
• Observational Model: CASE CONTROL
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER GOV
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: January 24, 2025
• First Posted: January 30, 2025
• Study Start: March 31, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): March 1, 2029
• Last Updated: December 5, 2025

Record last verified: 2025-11

Locations

FR (1)