Psilocybin in Functional Neurological Disorder

The goal of this study is to learn about the brain network response in people who have functional neurological disorder who are administered with a single dose of the psychedelic psilocybin with therapeutic support.The main question it aims to answer is:Can the default mode network, a brain network thought to be relevent in FND, be modified by the administration of psilocybin based on functional magnetic resonance imaging before and after the dose?

Inclusion Criteria:Age 25 - 60 years.Fluent in the English languageA diagnosis of FND from a neurologist and/or neuropsychiatrist as per DSM-5 criteriaModerate or severe symptoms (≥4 on Clinical Global Impression Severity (CGI-S) scale) which have been present for >12 months and have failed to respond to best available treatment.Able to tolerate fMRI scanning procedures.Failed to respond is defined as an inadequate response to a full course of FND-specific therapy, including psychological therapy (cognitive behavioural therapy) or physiotherapy. Either therapy must have been undertaken by a suitably trained expert in FND and must have been specifically targeted at FND symptoms.Exclusion Criteria:Diagnosis of severe depression (defined as meeting DSM-5 criteria) on the MINI 7.0. Positive diagnoses on the MINI will be subject to confirmation at clinical interview by a psychiatrist.Diagnosis of bipolar affective disorder (defined as meeting DSM-5 criteria for bipolar I or bipolar II) on the MINI 7.0. Positive diagnoses on the MINI will be subject to confirmation at clinical interview by a psychiatrist.Diagnosis of a psychotic disorder (defined as meeting DSM-5 criteria) on the MINI 7.0, EXCEPT substance/medication induced psychotic disorder where the duration was limited to the acute period of direct intoxication with the substance/medication. Positive diagnoses on the MINI will be subject to confirmation at clinical interview by a psychiatrist.Diagnosis of drug or alcohol dependence disorder (defined as meeting DSM-5 criteria) on the MINI 7.0. Positive diagnoses on the MINI will be subject to confirmation at clinical interview by a psychiatrist.Diagnosis of a personality disorder (defined as meeting DSM-5 criteria) on the MINI 7.0. Positive diagnoses on the MINI will be subject to confirmation at clinical interview by a psychiatrist.Diagnosis of any dementia (defined as meeting DSM-5 criteria for any dementia disorder) based on clinical interview by a psychiatrist.Diagnosis of any autistic spectrum disorder (defined as meeting DSM-5 criteria for any dementia disorder) based on clinical interview by a psychiatrist.Diagnosis of any learning disability (defined as meeting DSM-5 criteria for any dementia disorder) based on clinical interview by a psychiatristSignificant suicidal behaviour in past 12-months defined using the Columbia-Suicide Severity Rating Scale (C-SSRS) and confirmation based on clinical interview by a psychiatristAny other factor which would render the participant unsuitable for psilocybin and/or interfere with a supportive therapeutic relationship and/or preclude safe follow-up.Those unable to give informed consentMedical diagnosis incompatible with psilocybin treatment (see Section 8.2.1)Inability to provide a screening blood sample, urine sample or electrocardiogram.Biochemical abnormalities (defined as falling outside the normal reference range) as evaluated by a full blood count, full biochemistry profile and thyroid function tests. Biochemical abnormalities must also be determined as clinically significant by a medical doctor to fulfil the criterion for exclusion.Electrocardiographic abnormalities, defined as any abnormality that is not normal sinus rhythm and determined as clinically significant by a medical doctor.Women of childbearing potential not using contraception.Pregnant or breast-feeding women.Non-registration with a GP or failure to consent to sharing of the GP summary care record and any psychiatric assessments held.Those enrolled in another clinical or research study.Use of any psychedelic substances >2 times in past 12 months.Any factor which would exclude the participant from magnetic resonance imaging (e.g., presence of metal)