Synaptic Loss in Multiple System Atrophy

"All participants will undergo a collection of demographic data, a neurological examination and administration of clinical scales relevant for MSA-P. All participants will undergo a collection of venous blood sample for routine analyses.~Participants will undergo one PET scan with the tracer \[11C\]UCB-J, and one PET scan with the tracer \[18F\]FDG. All participants will also undergo one MRI scan.~Participants will also undergo one lumbar puncture (optional).~All procedures will be performed at baseline and after one-year follow-up."