Which sign is most characteristic of Parkinson’s disease and often used as a key diagnostic clue?

Which sign is most characteristic of Parkinson’s disease and often used as a key diagnostic clue?

• A. Unsteady gait
• B. Muscle rigidity
• C. Hyperactive reflexes
• D. Bradykinesia

Answer: (D)

Slowness of movement, or bradykinesia, is the sign most characteristic of Parkinson's disease and is used as a key diagnostic clue. The disease involves loss of dopaminergic neurons in the substantia nigra, which impairs initiation and speed of voluntary movements. This manifests as noticeably slow movements, difficulty starting tasks, reduced arm swing, slowed finger tapping, and trouble rising from a chair—features that are central to the diagnosis. While muscle rigidity and a shuffling gait commonly accompany bradykinesia, and unsteady gait can occur, these are less specific. Hyperactive reflexes are not typical of Parkinson’s. So the defining feature clinicians rely on is the marked slowing of movement.