Parkinson's disease (PD) is a movement disorder. The symptoms get worse over time and can include:

  • Muscle rigidity
  • Tremor at rest
  • Slowing down of movements (bradykinesia)
  • Difficulty moving and gait instability

Part of the Brain Affected by PD—Yellow Section
Substansia Nigra
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PD is caused by a loss of certain nerve cells in the brain. The loss of these cells causes a decrease in the amount of a brain chemical called dopamine. Low dopamine levels cause PD symptoms.

The brain cells may be lost because of genetic defects, the environment, or some combination of the two. A small amount of people with PD have an early-onset form. This type is caused by an inherited gene defect.

Secondary PD has similar symptoms but is caused by several factors such as:

  • Antipsychotic drugs, such as haloperidol (Haldol), fluphenazine (Prolixin), trifluoperazine (Stelazine), and chlorpromazine (Thorazine)
  • Antinausea/gastric motility medications such as prochlorperazine and metoclopramide
  • Cardiovascular drugs, such as some calcium channel blockers and antiarrhythmic drugs
  • Valproic acid (a medication used for seizures, migraines, and bipolar disorder)
  • Carbon monoxide poisoning
  • Manganese poisoning
  • Hydrocephalus
  • Brain tumors
  • Stroke
  • Encephalitis
  • Meningitis
  • IV drug abuse contaminated by MPTP (a type of neurotoxin)
  • Reserpine (medicine to treat schizophrenia and high blood pressure)
  • Insecticide exposure
  • Trauma
  • AIDS