Parkinson's disease is a progressive neurologic disorder that typically occurs in older adults and results in slowed movements, tremors, and rigidity. It is caused by the loss of cells in the substantia nigra region of the brain, which decreases the production of dopamine in the striatum. Over time, motor and neuromuscular changes can lead to impairments in mobility, breathing, elimination, and nutrition that cause increased dependence on others for care. Death usually occurs within 7-10 years from complications like dysrhythmia or pulmonary embolism.