An interventional study of Cognitive Behavioral Therapy in Idiopathic Environmental Intolerance, sponsored by Institut National de la Santé Et de la Recherche Médicale, France. Recruiting at 1 site in France. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-08-13.
Sponsored by Institut National de la Santé Et de la Recherche Médicale, France · Not applicable, Interventional, and Treatment
Idiopathic Environmental Intolerance (IEI) denotes a functional disorder represented by heterogeneous symptoms that sufferers attribute to specific environmental agents and for which there may be no solid evidence of an underlying physiological cause.
We are conducting a randomized controlled trial study to compare patients before and after a newly developed cognitive behavioral therapy treatment program for IEI, with respect to behavioral and psychometric variables.
The results of this research project are expected to contribute to advancements in the clinical treatment of IEI, as well as to elaborate on existing theoretical models of IEI.
Introduction:
A percentage of the population report various, nonspecific somatic and cognitive symptoms (e.g., headaches, nausea, fatigue, difficulty concentrating...) that they causally attribute to agents in their environments (chemicals, electromagnetic fields, windmills..). This condition is called Idiopathic Environmental Intolerance (IEI). It is proposed that the attribution of symptoms to an environmental agent, and the associated negative expectations is what drives symptom experience. We hypothesize that this, alongside other cognitive biases, are involved in the emergence and maintenance of symptoms. Treatment models have been developed, but no cognitive behavioral therapy was tested on IEI patients.
The planned study aims to investigate the feasibility and efficacy of a cognitive behavioral treatment online program, in ameliorating quality of life in a French population of patients suffering from IEI.
Methods and analysis:
This parallel two-armed, randomized controlled trial, evaluates an 8-week guided intervention against a wait-list control group. It is a hybrid intervention that will include web-based consecutive modules based on disorder-specific cognitive behavioral therapy (CBT) as well as general transdiagnostic principles . Guidance will be provided by trained psychologists with weekly supportive feedback.
As part of the "BELIEF" project, the present study aims to recruit n=82 patients indicating symptom attributed to factors in the environment. Assessments will take place at baseline and after intervention completion (12 and 24 weeks after randomization). The primary outcome will be measured by the SF-12 scale for quality of life. Secondary outcomes include symptom perception, severity and distress, eco-anxiety, emotional processing, intolerance to uncertainty and associated mental disorders such as depression and anxiety. Consumption of healthcare services will also be measured.
Ethics and dissemination:
Ethics approval has been granted. Results from this study will be published in peer-reviewed journals and presented at international conferences.
Trial registration number: DRKS00014375
71 studies on the registry are indexed under Medically Unexplained Symptoms; 22 are open to participants now.
This study's planned enrollment of 82 is above the median of 68 across 53 interventional studies indexed under Medically Unexplained Symptoms.
Browse Medically Unexplained Symptoms studies →Institut National de la Santé Et de la Recherche Médicale, France is the lead sponsor of 378 studies on the registry; 81 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Behavioral: Cognitive Behavioral Therapy
Behavioral: Cognitive Behavioral Therapy
CBT for IEI
Short Form Health Survey - 12
Measures quality of life with a minimum value of zero and a maximum value of 100. Higher score indicates better outcome.
Time frame: T0; 3 Months ; 6 Months
The Somatic Symptom Disorder - B Criteria Scale
Measures criteria for Somatic Symptom Disorder (SSD) and symptoms' burden: The total score ranges between 0 and 48, with a higher score reflecting higher levels of the psychological features of the SSD, or worse outcome.
Time frame: T0; 3 Months ; 6 Months
Symptom Interpretation Questionnaire
Measures causal attributions individuals make of common somatic symptoms by using three sub scales: somatic (range 13-36), psychological (range: 13-52), and environmental/normalizing (range: 17-49). Each sub score represents the extent with which each sub scale is endorsed as a possible cause for symptoms (higher score means higher outcome).
Time frame: T0; 3 Months ; 6 Months
QEESI (Quick environnemental exposure and sensitivity inventory)
Measures Chemical Sensitivity with 5 subscales: Symptoms, Chemical Intolerances, Other Intolerances, Masking, and Life Impact. Patients with no intolerance to chemicals only complete the subscales on Symptoms.
Time frame: T0; 3 Months ; 6 Months
11-item Electromagnetic Field Sensitivity Scale
Measures sensitivity to Electromagnetic Fields. The score can range from 0 to 54 (high score representing high annoyance/intolerance and worse outcome). Only patients reporting intolerance to Electromagnetic fields complete this questionnaire.
Time frame: T0; 3 Months ; 6 Months
Modern Health Worries Scale short (12-item) version
Measures Modern Health Worries (concerns of respondents about modern environmental issues). Scores range from 12 to 60 with higher scores indicating more concern or worse outcome.
Time frame: T0; 3 Months ; 6 Months
Climate Change Anxiety Scale
Measures Climate Change Anxiety with scores ranging from 13 to 65 and higher scores indicating higher levels of climate change anxiety, or worse outcome.
Time frame: T0; 3 Months ; 6 Months
Hospital Anxiety and Depression scale
Measures Depression and Anxiety. Score ranges from 0 to 21 with higher score representing worse outcome.
Time frame: T0; 3 Months ; 6 Months
Short version of the Intolerance of Uncertainty Scale
Measures Intolerance to Uncertainty with total scores ranging from 12 to 60 with higher score representing worse outcome. The total scores encompasses two sub-scales: prospective anxiety and inhibitory anxiety. A greater score in each subscale indicates a greater level of prospective anxiety and inhibitory anxiety.
Time frame: T0; 3 Months ; 6 Months
Body Perception Questionnaire - Very Short Form
Measures body awareness and autonomic stress response patterns. Scores range from 12 to 60. Particularly high scores may indicate the autonomic nervous system is frequently activated by stress or chronic threat responses (i.e. worse outcome)
Time frame: T0; 3 Months ; 6 Months
Levels of Emotional Awareness Scale 10 item
Measures the Level of Emotional Awareness with a maximum score of 50. Higher scores indicating greater awareness and differentiation in emotions, or better outcome.
Time frame: T0; 3 Months ; 6 Months
Attitudes Towards Seeking Mental Health Services Inventory (IASMHS)
measures how people think and feel regarding utilizing psychological healthcare. This 24-item scale assesses 3 internally consistent factors: psychological openness, help-seeking propensity, and indifference to stigma. Participants answer the questions using a 5-item scale (0 = disagree; 4= agree). Higher scores on the indifference to stigma scale reflect a positive stance towards mental healthcare services, while higher scores on the other two subscales reflect a more negative attitude.
Time frame: T0
healthcare utilization questionnaire
Consists of 6 questions with an open answer format and assesses the number of medical and paramedical visits, therapists' visits, physical exams, as well as medication and dietary supplements consumed over the last 3 months.
Time frame: T0, 3 months, 6 months
Working Alliance Inventory
Measure three dimensions of working alliance: agreement on therapeutic goals, consensus on tasks, and affective bond between client and therapist. The questionnaire consists of eight items measured on a five-point scale (1=never to 5=always), as well two open questions for feedback to the therapist. A higher score indicates a better client-therapist relationship.
Time frame: filled out after 3 weeks into treatment by the therapist.
Affect and Symptom Paradigm
Studies how negative affective stimuli influence somatic symptom perception. Negative and neutral pictures are presented to participants and after each picture series, participants fill in a short questionnaire about their current symptoms and affective state.
Time frame: t0, 3 months, 6 months
Attribution Bias task
Monitors symptoms during 2X10 mins exposure to environmental agents patients attribute symptoms to (wifi box or chemicals) and 1X10 mins control without exposure. Patients can stop the task at all times.
Time frame: t0, 3 months, 6 months.
Belief Updating Task
This task was developed to investigate information processing and belief updating in light of desirable or undesirable information. Patients rate their own risk for negative events, some of them related to environmental hazards, as compared to baseline risks in the general population.
Time frame: t0, 3 months, 6 months.
Client Satisfaction Questionnaire
Explores patients' feedback after receiving the traitement protocole, in 8 questions from 1 to 4 (high score representing high satisfaction) and 2 open questions for comments and suggestions.
Time frame: either 3 months (intervention group) or 6 months (waitlist group)
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