Parkinson’s Disease (PD) is the second most common age-related neurodegenerative disorder after Alzheimer’s Disease. It affects approximately 1 million people in the United States, with an estimated 60,000 new cases being diagnosed each year. PD is a chronic, progressive movement disorder typically characterized by at least 2 of 4 cardinal features: tremor (mainly at rest), stiffness or rigidity of muscles, bradykinesia (slowness of movement) and gait and balance problems.

PD occurs when nerve cells in a very specific region of the brain called the substantia nigra stop working or die. These nerve cells, or neurons, produce a specific type of neurotransmitter, dopamine, which helps to regulate movement. As dopamine levels in the brain decrease over time, patients experience impaired movement and other symptoms of PD. In addition to the cardinal features of PD, Parkinson’s patients may also experience non-motor symptoms including cognitive impairment, sleep disorders, pain and fatigue.

There is presently no cure for Parkinson’s Disease. The current gold standard for management of PD symptoms is Levodopa (L-dopa), a medication developed in the late 1960s that treats motor symptoms. L-dopa is synthesized in the brain into dopamine and is considered the most important first-line drug for the management of PD. Over time, patients begin to see the beneficial effects (“ON” time) of L-dopa wear off more quickly and they develop motor fluctuations (“OFF” time). Additionally, approximately 50% of patients on L-dopa long-term (longer than four years) experience Levodopa-induced dyskinesia (LID), which is described as involuntary, erratic, writhing movements of the face, arms, legs and/or trunk. Some Parkinson’s patients delay the use of L-dopa because of the concern regarding the development of dyskinesias.

https://www.parkinson.org/understanding-parkinsons/what-is-parkinsons