Which statement best describes Parkinson's disease?

• A. It is a cerebrovascular disorder
• B. It is a motor system disorder that is slowly progressive and degenerative
• C. It is an inflammatory disease of the peripheral nerves
• D. It is a psychiatric condition with mood fluctuations

Answer: (B)

Parkinson's disease is a motor system disorder caused by loss of dopamine-producing neurons in the substantia nigra, which leads to reduced dopamine in the basal ganglia and disrupts movement control. This neurodegenerative change produces the hallmark motor symptoms—resting tremor, rigidity, bradykinesia, and eventual postural instability—that progress slowly over time. Because its primary impact is on motor function and it progresses gradually over years, it’s best described as a slowly progressive and degenerative motor system disorder. It isn’t a cerebrovascular issue (that would involve blood vessel problems like a stroke), nor an inflammatory disease of the peripheral nerves, and while mood changes can occur, it isn’t classified as a psychiatric condition with primary mood fluctuations.