After Alzheimer’s disease, Parkinson disease is the most common neurodegenerative disease.
This chronic, progressive disease results when nerve cells in a part of the midbrain, called the substantia nigra, die or are impaired. These nerve cells produce dopamine, an important chemical messenger that transmits signals from the substantia nigra to another part of the brain called the corpus striatum. These signals allow for coordinated movement. When the dopamine-secreting cells in the substantia nigra die, the other movement control centers in the brain become unregulated. These disturbances in the control centers of the brain cause the symptoms of PD. When 80% of the dopamine-producing cells in the substantia nigra are depleted, symptoms of PD develop.
Patients are aware of the progressive nature of the illness and the illness can become a source of much anxiety. Concern about the progression of the disease and the ability to continue working and socializing is frequently voiced.
It is not possible to predict with any confidence the likely course of the disease in an individual patient. The rate of progression and resulting level of disability vary in different patients.
When the disorder is such that normal activities of daily living are impaired, at least to some extent, symptomatic treatment is begun with medication; and thus a life of adjusting medication dosages and types begins. As you increase dosages of the symptom controlling medication, new challenges arise from the side effects and start to affect the PD patient. Hallucinations and dyskinesia (involuntary trunk body movements) are a few of the main concerns.