Gait Analysis in Neurological Disease

Inclusion Criteria: * Age 18-85 (for both healthy and affected subjects). * Presence of at least 2 of the following: bradykinesia, rest tremor, rigidity, postural instability (UK PD Brain Bank Criteria) (Affected subjects only). * Montreal Cognitive Assessment will be employed to determine whether subjects will need the assent of a legally authorized representative. Subjects with MOCA ≤ 21 will be consented only with the assent of the subject and informed consent of the authorized legal representative (Affected subjects only). * These may include subjects who may have indeterminate parkinsonism, when it is not clear whether they have idiopathic Parkinson's Disease versus one of the Atypical Parkinsonisms, such as Vascular Parkinsonism, Multiple System Atrophy, Progressive Supranuclear Palsy, Normal Pressure Hydrocephalus or Corticobasal Degeneration (Affected subjects only). * Subjects with assistive devices will be eligible for the study and may use them during the study (Affected subjects only). * Absence of complaints regarding difficulty walking such as arthritic pain, fatigue during walking or slowness of walking (Healthy subjects only). Exclusion Criteria: * Presence of alternative explanation for parkinsonism such as head trauma, drug-induced parkinsonism (affected subjects only). * Currently being treated for major medical illness requiring recent hospitalization (\<14 days) (for both healthy and affected subjects). * Currently participating in another clinical study with an intervention arm (for both healthy and affected subjects). * Inability to consent due to cognitive impairment and absence of legally authorized representative (for both healthy and affected subjects). * Subjects with any cardiac, pulmonary conditions (congestive heart failure requiring hospitalization within the past 90 days, recent myocardial infarction \< 90 days, supplemental oxygen-requiring subjects due to cardiac or pulmonary conditions) that limit their ability to safely participate in a walking trial (for both healthy and affected subjects).