Parkinson’s Disease

What is Parkinson’s Disease? Parkinson’s disease (PD) is a neurodegenerative movement disorder involving a progressive loss of dopamine-producing cells in the midbrain. Close to one million people in the United States have been diagnosed with Parkinson’s disease and the global prevalence is estimated to be around ten million. The age of onset is generally over 50 and the incidence increases with age. However, four percent of patients are diagnosed prior to turning 50.

What Causes Parkinson’s Disease?

Parkinson’s disease is characterized by neurodegeneration of the dopaminergic cells in the substantia nigra pars compacta and their terminals in the basal ganglia, as well as the development of associated Lewy bodies. Impairments in movement are often obvious only after the destruction of a large number of cells. The development of Parkinson’s disease is likely multifactorial, influenced by the interaction of genetic susceptibility and environmental factors. 

Risk factors include:

  • Exposure to chemical toxins, especially pesticides
  • History of head trauma
  • Genetic variants near gene encoding alpha-synuclein.
  • Higher intake of dietary dairy.
  • Family history of Parkinson’s disease.
  • Male gender

Symptoms of Parkinson’s Disease

Early signs of Parkinson’s disease:

  • Resting tremor
  • Micrographia
  • Anosmia
  • Restless sleep from insomnia, REM behavior disorder, or restless leg syndrome
  • Stiffness and difficulty in movement
  • Constipation
  • Change in voice
  • Masked facies
  • Dizziness or fainting
  • Stooping

Characteristic symptoms of impaired movement:

  • Bradykinesia
  • Tremor
  • Rigidity

Additional symptoms include:

  • Dystonia
  • Drooling
  • Dyskinesia
  • Festination
  • Freezing, or the appearance of being stuck in place
  • Shuffling gait
  • Depression and other changes in mood
  • Cognitive changes
  • Hallucinations and delusions
  • Postural instability later in disease

Source: Simon, D. K., Tanner, C. M., & Brundin, P. (2020). Parkinson Disease Epidemiology, Pathology, Genetics, and Pathophysiology. Clinics in Geriatric Medicine, 36(1), 1–12.