Clinical Evaluation of HRV Biofeedback in Functional Neurological Disorders Compared to Placebo

Evaluation of the clinical effects of the Heart Rate Variability biofeedback training with patients suffering from Functional neurological Disorders compared with placebo.

Inclusion Criteria: * Functional Neurological Disorders (FND) diagnosis must be medically established * Participants must have a smartphone (android ou Iphone) * Participants must be of the age of majority * Participants must have signed an informed consent * Sufficiently fluent in French to understand study documents and instructions * Consistency in performing repeated questionnaires * Normal or corrected-to-normal visual acuity Exclusion Criteria: * Specially protected participants: juveniles, pregnant womens, nursing mothers, law's protection peoples * Participants suffering from a severe psychiatric disease needing specialised attention * History of severe neurosurgical pathology * Alcohol dependence or drug use * Participants suffering from or have suffered from a severe disease causing autonomic dysfunctions (heart failure, asthma, blood disease, renal failure, peripheral neuropathy, vagotomy, thyroid disorder, alcoholism, liver disease, amyloidosis) * Participants taking medication which could be impact autonomic nervous system activity (anticholinergic, antiarrhythmics, clonidine, beta-blockers, tricyclic anti-depressants, metronidazole) * Participants placing under judicial or administrative supervisions