|Parkinson’s disease is a progressive, neurological condition resulting from the loss of dopamine, a neurotransmitter (or chemical messenger) produced in the part of the brain that controls movement. When 60-80% of the dopamine cells have been lost, the symptoms appear. Why this happens is currently unknown. Genetics and environmental factors are amongst the areas of research currently being investigated
Symptoms usually appear in people over 50 years and the risk of having the condition increases with age. However, younger people can also have Parkinson’s disease, of the 10,000 people diagnosed each year in the UK, one in 20 will be aged under 40 years.
More info: NHS Direct