Investigation of the Serotoninergic System in Multiple System Atrophy: a Positron Emission Tomography (PET) Study

Inclusion Criteria: * Patients with Multiple system atrophy (MSA) * MSA possible or probable * Male and female * Age : 30 to 80 * No cognitive impairment * Unmodified treatment for 2 months * Able to give informed consent * Affiliated to social insurance * Patients with idiopathic Parkinson's disease (IPD): * Positive clinical criteria for IPD * Male and female * Age : 30 to 80 * No cognitive impairment * Unmodified treatment for 2 months * Able to give informed consent * Affiliated to social insurance * Healthy controls: * Absence of neuropsychiatric disorder * Male and female * Age : 30 to 80 * Able to give informed consent * Affiliated to social insurance Exclusion Criteria: * Patients with Multiple system atrophy (MSA) * Other Parkinsonian syndrome * Dementia * Recent intake (\< 4 weeks or 8 weeks for fluoxetine) of medication acting on 5-HT1a receptors * History of major depression * Contraindication to brain MRI * Contraindication to PET * Patients with idiopathic Parkinson's disease * Other Parkinsonian syndrome * Dementia * Recent intake (\< 4 weeks or 8 weeks for fluoxetine) of medication acting on 5-HT1a receptors * History of major depression * Contraindication to brain MRI * Contraindication to PET * Healthy controls: * Patient having a neuropsychiatric disease * Recent intake (\< 4 weeks or 8 weeks for fluoxetine) of medication acting on 5-HT1a receptors * History of major depression * Contraindication to brain MRI * Contraindication to PET