Parkinson's disease. Artwork representing Parkinson's disease showing an elderly man standing in a characteristic hunched position. At left are assorted connected nerve cells. Parkinson's disease is a disorder of the nerve cells in the brain, which causes degeneration of dopamine producing nerve cells. This leads to muscle tremors, a staring expression and the rigid, stooped posture seen here. There is no cure for Parkinson's disease, although some drugs (such as levodopa) appear to help the symptoms for a short time. As the disease progresses, severe incapacitation develops, which may be followed by dementia.