Evaluation of the Effect of a Single Dose of Psilocybin on Neural Correlates of Cognitive Control in Patients With Psychogenic Nonepileptic Seizures

Inclusion Criteria: * Euthymic patient according to the MINI questionnaire. * Diagnosis of PNES confirmed by video-EEG, progressing for more than 3 months, and meeting DSM5 criteria. * Normal brain MRI during the assessment as part of routine care * No contraindication to stopping any antidepressant treatment for a fortnight (or 5 weeks for fluoxetine) prior to the administration of psilocybin. Other psychotropic treatments will not be interrupted. * Patient must have given their free and informed consent and signed the consent form * Patient must be a member of beneficiary of a health insurance plan * Patient available for a total of 6 months follow-up. * Good physical health and absence of unstable medical pathology. These pathologies include cardiovascular co-morbidities: history of stroke, myocardial infarction, heart failure, arrhythmia, uncontrolled hypertension (greater than 165/95 mmHg at screening); organic epileptic syndrome and active neurological comorbidities; endocrine pathologies (dysthyroid and adrenal insufficiency, type 1 diabetes or insulin-requiring type II diabetes, history of severe hypoglycaemia requiring hospital treatment); considerable impairment of liver function; glaucoma; symptomatic prostatic hypertrophy or bladder neck obstruction. * Ability to understand and speak French Exclusion Criteria: * Serious risk of suicide according to the clinician opinion. * High risk of adverse emotional or behavioural reaction as clinically assessed by the inve…