Walking difficulties Symptoms tend to occur asymmetrically at the beginning for example, affecting one arm but not the other. This may persist indefinitely. Sometimes only a single symptom is present for months before others develop. Parkinson's disease belongs to a group of conditions called motor system disorders. Parkinson's and related disorders are the result of the loss of dopamine-producing brain cells.
Dopamine is a chemical messenger responsible for transmitting signals within the brain.
Loss of dopamine causes other nerve cells to fire out of control, leaving patients unable to direct or control their movement in a normal manner. Although no cure exists for Parkinson's disease, a variety of effective medications may provide dramatic relief of symptoms. The cause of Parkinson's disease is unknown. Some cases of Parkinson's disease appear to have a genetic component. It's a complex and enigmatic neurological disorder that most often affects people age 55 and older.