Parkinson's disease is a degenerative disease of the nervous system which increases in severity over time.
In Parkinson's disease, neurons (nerve cells) of the brain area known as the substantia nigra are primarily affected. When these neurons degenerate, the brain's ability to generate body movements is disrupted and this disruption produces signs and symptoms characteristic of Parkinson's disease, such as:
- Tremor
- Rigidity
- Lack of movement or loss of spontaneous movement
- Slowness of movement
- Problems with walking and posture
Because Parkinson's disease is a progressive disorder, we can generally expect the signs and symptoms of the disease will become more pronounced each year. No one can accurately predict how, or how quickly, the disease will progress in a specific individual.
With time, a person's degree of motor disability does tend to increase, however, and after five to 10 years of illness the symptoms will disrupt daily life. At this point, medications are needed in higher doses and must be monitored and adjusted more frequently.
As Parkinson's becomes more advanced, facial movement, blinking and spontaneous smiling and expression all become more difficult, and people have increasing difficulty functioning independently. However, many people with Parkinson's never reach this stage, because they live a normal life span and continue to receive significant benefit from their anti-parkinson medications.