An observational study in Functional Neurological Disorder, sponsored by University of Fribourg. Completed at 2 sites in Switzerland. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-03-27.
Sponsored by University of Fribourg · Observational
The main goal of this project is to better understand the role of oxytocin and Interoception in FND. More specifically oxytocin's association with precision weighing, prediction errors and priors in the interoceptive domains will be investigated. To this end, several methods will be employed: analysis of interoceptive accuracy and sensibility (interoceptive tasks and questionnaires), biomarkers of oxytocin (peripheral, endogenous oxytocin), genetic oxytocin markers (such as allele-frequency in the oxytonergic receptor gene), epigenetics (methylation rates of genes related to oxytocin), neuroactivity (EEG).
The primary objective is to explore interoceptive processing during a behavioural (interoceptive) tasks and its association to the oxytocin (OT) system in patients affected by a functional neurological disorder (FND), in comparison to healthy controls (HC).
Concerning interoception, as primary outcome, it is hypothesized that:
A) FND patients are less interoceptive (judged by objectively measured accuracy) compared to HC in the interoceptive tasks.
Concerning OT, as primary outcome, it is hypothesized that:
B) The OT level is correlated with interoception tasks; specifically the adaption of precision weighting
The secondary objectives are to:
89 studies on the registry are indexed under Conversion Disorder; 34 are open to participants now.
This study's enrollment of 110 is above the median of 60 across 37 observational studies indexed under Conversion Disorder.
Browse Conversion Disorder studies →University of Fribourg is the lead sponsor of 16 studies on the registry; 7 are open to participants now.
Counted across the registry records on this site, refreshed daily.
FND patients Participants who are patients will be recruited from the in- and out-patients pool of the Clinic for Neurology of the Hospital of Fribourg and the Inselspital. At both, the treating physician will identify suitable patients (i.e. patients who fulfil the clinical requirement for FND as described in the DSM-5). The treating physician will ask these patients whether they would like to be approached by the Investigator (or his/her designee) concerning a scientific study. In case of affirmative response, the Investigator will approach the patients, inform them about the study.
Healthy control Healthy controls will be recruited among students, collaborators, and visitors of the University of Fribourg and Bern, the Hospital of Fribourg and the Inselspital. They will be recruited by flyer, by word-of-mouth and through advertisements in public media.
Inclusion Criteria for Patients:
Inclusion Criteria for Healthy controls:
Exclusion Criteria for Patients:
Exclusion Criteria for Healthy controls:
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.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
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.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Group of patients with functional neurological disorders
Device: Respiration resistance sensitivity task (RRST) · Behavioral: Heartbeat Tracking (HBT) · Device: Heartbeat evoked potential (HEP) · Device: Libet task
Age matched group control of healthy participant
Device: Respiration resistance sensitivity task (RRST) · Behavioral: Heartbeat Tracking (HBT) · Device: Heartbeat evoked potential (HEP) · Device: Libet task
The RRST measures interoception on the domain of the breath and thus allows its (non-invasive) manipulation. The RRST apparatus includes a step motor that moves a wedge piece back and forth to change the obstruction level in the breathing circuit. This fully automated apparatus will change the breathing obstruction level via a computer-controlled algorithm. The patient breath by the month though this device.
Also known as: Respiration resistance device
The HBT measures interoception on the domain of the cardiovascular system, by assessing how accurate participants perceive their own heartbeat. After each time window participants will be asked how many heartbeats they counted, which will be compared to the actual heartbeat measured via electrocardiography (ECG).
Also known as: ECG
The HEP is computed by averaging EEG signals time-locked to specific peaks of simultaneously measured ECG signals. Therefore both an ECG and an EEG will be set up for the participants. The task during the HEP is to simply focus on interoceptive tones (the own heartbeat) with a control condition of focusing on exteroceptive tones (sounds played). A further condition of HEP measurement is the cardio-audio synchronization. Hereby, participants will be instructed to passively listen to sounds presented to them via in-ear phones while further fixating the cross.
Also known as: ECG + EEG
Additionally we also link the interoceptive domain of the breath to a well-known and established agency task measuring conscious intention. Participants will do two versions of the Libet taks while simultaneously recording their EEG and breathing signals with a respiratory belt.
Also known as: Respiration belt + EEG
Difference of interoception behavioural scores between FND patients and Healthy controls
Assessment of the difference between interoception tasks scores between these groups. These scores evaluated the interoception processing abilities of patient/control.
Time frame: 1 day
Difference in brain electrophysiology during interoception processing between FND patients and Healthy controls
Assessment of the difference Evoked Related potential (ERPs) during interoception taks between these groups.
Time frame: 1 day
Association between oxytocin system and interoception and its difference between FND patients and Healthy controls
Study of the correlation between oxytocin system and interoception indices. Oxytocin system was studied with oxytocin concentration (saliva) and genetic markers (blood analysis).
Time frame: 1 day
Oxytocin concentration (Saliva sampling)
During the day of the experimental session, 4 samples of saliva at different time are collected. These sample will be used to determine the concentration of oxytocin during the day (30 min post awakening, 30min after lunch, at tasks, upon the arrival for experimental session, after the completion of all tasks).
Time frame: 1 day
Epigenetic profile
Blood sample are used for genetic analysis on the oxytocin markers (such as allele-frequency in the oxytonergic receptor gene). Correlation of this with interoceptive scores.
Time frame: 1 day
Respiratory Resistance Sensitivity
Difference of accuracy between FND patients and healthy control in the respiratory resistance sensitivity task.
Time frame: 1 day
Behavioral measure: heartbeat counting
Difference of accuracy between FND patients and healthy control to count the number of their own heartbeats.
Time frame: 1 day
Electrophysiological measure (EEG): Heartbeat evoked potential (HEP) task1
First, study the HEP difference between interoceptive tones (the own heartbeat) with a control condition of focusing on exteroceptive tones (sounds played). Then comparison between FND patients and healthy control.
Time frame: 1 day
Electrophysiological measure (EEG): Heartbeat evoked potential (HEP) task2
First, study the difference of mismatch negativity (MMN) evoked potential either if external tone was synchronous or asynchronous with heartbeat. Then comparison between FND patients and healthy control.
Time frame: 1 day
Neurophysiological measures: Correlation between agency task and respiration cycle (Libet)
Study of the correlation between a free will key press and the state in respiration cycle. Then comparison of the results between FND patients and healthy control.
Time frame: 1 day
Electrophysiological measure (EEG): the readiness potential (Libet)
Analysing the readiness potential related with the motor movement in the implicit compared to the explicit trigger. Then comparison of the results between FND patients and healthy control.
Time frame: 1 day
The localization of neuronal activity derived from EEG during interoceptive tasks, and during resting state
Use of the EEG signal during cardiac interception task (HEP),agency task (Libet) and resting to estimate the source generator of brain activities (inverse solution).
Time frame: 1 day
Behavioral measure: Correlation between oxytocin and clinical questionaire
Correlating the scores or categories of childhood trauma, attachment style and sexual functioning to oxytocin levels.
Time frame: 1 day
Plan to share: No
No publications or documents are linked to this record.
Ran from Oct 2023 to primary completion in Jan 2025, 15 months.
Of 16 observational studies under Conversion Disorder, half reached primary completion within 23 months of starting (the median), counting those still running; a quarter within 13 and three quarters within 55. This study's 15 months is below that.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Mar 2025. You cannot join it, but the record below documents what was studied.
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University of Fribourg