Natural History and Disease Progression Biomarkers of Multiple System Atrophy

INCLUSION CRITERIA: Applicable to MSA patients: * Patients with possible or probable MSA according to consensus diagnosis criteria \[Gilman et al., 2008\] * Patients aged between 30 and 80 years * Patients at the early stages of the disease, defined as maximum 5 years since the onset of one of the following symptoms associated to MSA: Parkinsonism Ataxia Orthostatic hypotension and/or urinary dysfunction - Patients with an anticipated survival of at least 3 years on the basis of Investigators' clinical judgment Applicable to healthy controls: * Participants with a similar age (+/- 5 years) and gender distribution compared to MSA patients * Participants with absence of neurological pathology * Patients aged between 25 and \< 80 years Applicable to both patients and healthy controls: \- Participants who voluntarily sign the written informed consent form, indicating that they understand the purpose of and procedures required for the study and are willing to participate in it Participants affiliated to the French social security health system EXCLUSION CRITERIA: Applicable to MSA patients: * Speech impairment (score of ≥3 on UMSARS (Unified Multiple System Atrophy Rating Scale) question 1); * Impairment in ambulation (score of ≥3 on UMSARS (Unified Multiple System Atrophy Rating Scale) question 7) * Falling more frequently than once per week (score of ≥3 on UMSARS (Unified Multiple System Atrophy Rating Scale) question 8) Applicable to both MSA patients and healthy controls: * Participants with significant cognitive impairment (MoCA score \<21) * Any major medical or psychiatric condition which may compromise participation in the study or the safety, at the discretion of the Investigator * Contraindications for MRI imaging, including claustrophobia and presence of metallic implants such as cardiac or auditory prostheses, pacemakers or cerebral clips * Contraindications to obtain a FP-CIT SPECT(Single Photon Emission Computed Tomography) (i.e. known hypersensitivity to the active substance or to any of the excipients, or to iodine) * Current pharmacological treatments that may alter the DAT(dopamine transporter ) SPECT (Single Photon Emission Computed Tomography) reading, including amphetamines, benzatropine, buproprion (amfebutamone), cocaine, mazindol, methylphenidate, phentermine or sertraline * Females who are pregnant, breast feeding or of child bearing age without effective contraception * Participants who lack the capacity to give informed consent * Participants taking any investigational products within 3 months before baseline assessment * Participant under adult autonomy protection system, legal guardianship or incapacitation. Additional exclusion criteria concerning only patients consenting to the lumbar puncture: * Coagulopathy and/or anticoagulant treatment * Thrombocytopenia * Intracranial hypertension * Severe degenerative arthritis of the lumbar spine Patients failing to meet these criteria can still participate in the study and all other study assessments (with the exception of lumbar puncture) as appropriate.