Parkinson's disease is a progressive nervous system disorder that results from the loss of dopamine-producing neurons in the substantia nigra. It is characterized by tremors, stiffness, and slow movement. Approximately 1 in 100 people over 60 are affected, with 1.5 million cases in the United States where 58% are men. While there is no cure, treatment focuses on replenishing dopamine levels through levodopa/carbidopa drugs and potentially surgery.