Parkinson's disease occurs when certain nerve cells, or neurons, die or become impaired.
Normally, these neurons produce dopamine and other neurotransmitters. Dopamine is a chemical messenger responsible for transmitting signals within the brain.
Loss of dopamine results in patients being unable to direct or control their movement in a normal manner. Parkinson's is not usually inherited.
Treating Parkinson's disease
Symptoms of Parkinson's disease
What is Parkinson's disease?
Revised and reviewed by Prof Carr February 2015. Reviewed by Dr Andrew Rose-Innes, MD, Department of Neurology, Yale University School of Medicine, New Haven.