Genotypic Influences on Network Progression in Parkinson's Disease

Subjects will be tested for GBA and LRRK2 mutation status at baseline.

18F-Fluoro-2-deoxy-glucose (FDG) PET scan is a nuclear medicine test that measures glucose metabolism (energy) in your brain at baseline and 18 months later.

Magnetic Resonance Imaging (MRI) is a noninvasive scan which produces detailed pictures of the brain using a magnetic field. In addition, a special type of MRI, called resting state functional MRI (rs-fMRI), will measure and map brain activity. Conducted at baseline and 18 months later.

Investigator will evaluate subjects according to the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), the standard clinical tool used to measure the severity and progression of PD. Neuropsychological evaluation will assess how one's brain functions (via pencil and paper testing), which indirectly yields information about the structural and functional integrity of the brain. Conducted at baseline and 18 months later.