Which of the following symptoms is most characteristic of Parkinson's disease?

The hallmark symptoms of Parkinson's disease include a resting tremor, which is a tremor that occurs when the muscles are at rest and decreases with movement, as well as bradykinesia, which refers to slowness of movement. These symptoms arise due to the degeneration of dopamine-producing neurons in the brain, particularly in an area called the substantia nigra. The combination of tremor at rest and bradykinesia is particularly characteristic because they are core features commonly used in the clinical diagnosis of Parkinson's disease.

In addition to tremor and bradykinesia, patients may also exhibit other symptoms such as rigidity, postural instability, and changes in gait; however, the specific combination of resting tremor and bradykinesia is most definitive in identifying the disease. Recognizing these symptoms is crucial for early diagnosis and management of Parkinson's disease.