Parkinson’s disease is a progressive disorder that causes tremors (involuntary trembling movements, usually of the hands), slow movement, and stiffness.
It results from degeneration of cells in a part of the brain that produces dopamine, a chemical that helps to fine-tune muscle movements.
In Parkinson’s disease, the cells produce much less dopamine, resulting in impaired muscle control. In most people, there is no obvious cause of the condition, although genetic factors may be involved in some cases.
It can also result from an inflammation of the brain (encephalitis) or from damage to the basal ganglia from drugs or repeated head injuries.
The main symptoms are trembling of one hand, arm, or leg, which may progress to affect limbs on the opposite side; muscle stiffness, making it difficult to begin moving and making movements slower; and problems with balance.
Other symptoms may include a stooped posture, shuffling walk, problems speaking, loss of facial expression, and difficulty swallowing. Some people also develop dementia (opposite) or depression.
Treatment may include supportive therapies, such as physical therapy, and medication to improve symptoms. In some cases, surgery may be an option.