Summary: Background and Rationale Essential tremor (ET) affects over 6 million Americans and approximately 5% of adults over age 60. Patients with ET have a 10-20 times higher risk of developing Parkinson's disease (PD) compared to age-matched populations, with approximately 1% converting to PD annually. Post-mortem studies reveal Lewy body pathology in some ET patients, suggesting a subset may have prodro...

Summary: This study aims to study, in patient with Parkinson's disease, mild to moderate stage (according to Movement Disorder Society Clinical Diagnostic Criteria for Parkinson's Disease, Postuma et al., 2015): * the evolution of oculomotricity markers over time. * the correlation between neurological evaluations (motor and non-motor scores), neuropsychological evaluations (cognitive disorders) and oculom...

Summary: The purpose of this study is to identify and distinguish two different types of Progressive Apraxia of Speech through clinical imaging and testing.