What is Parkinson’s Disease?


Parkinson’s disease (PD) is a progressive neurologic disorder that is characterized by gradual loss of dopamine-producing cells in the brain.  Dopamine plays a role in controlling movements as well as in cognition, behavior, mood, attention, and sleep.

In many cases, symptoms associated with PD appear gradually, often affecting first one side of the body (uniteral) and progressing to include both sides (bilateral).   The following motor symptoms are described as cardinal features of PD, though it’s important to note that not all patients experience tremor, and the severity of specific symptoms may vary:

  • Bradykinesia, which is slowness of movement due to reduced ability to initiate voluntary movement
  • Tremor, often beginning in a hand.  Patients with PD may commonly develop a characteristic “back-and-forth” rubbing of the forefinger and thumb, sometimes called a “pill-rolling” tremor, that occurs when the hand is at rest.  (However, again, some PD patients may never develop tremor.)
  • Muscle stiffness (rigidity), which in some cases may first become apparent as decreased arm swing when walking
  • Impaired balance and coordination (postural instability)

Patients with PD may develop additional motor symptoms, including lack of facial expression, difficulty arising from a chair, trouble turning in bed, and unusually small handwriting (micrographia).

Non-motor symptoms may also be associated with PD, such as:

  • Diminished sense of smell
  • Speech changes
  • Depression
  • Cognitive changes
  • Low blood pressure on standing
  • Sleep disturbances
  • Constipation
  • Urinary urgency and frequency