Parkinson's Disease
Parkinson's disease is a progressive disease of the nervous system which affects around one person in every 500 in the UK. The disease becomes more common with increasing age. Symptoms usually first appear in people over the age of 50, although younger people can also develop the disease.
There is no evidence that Parkinson's disease is hereditary, although in around 5 per cent of cases there is another family member affected. It is believed that genetics may make some people more prone to developing Parkinson's disease but only if combined with exposure to external factors. To date, scientists have identified nine genes linked to Parkinson's disease.

Symptoms of Parkinson's Disease :
The main symptoms of Parkinson's disease are tremor, stiff muscles and joints, and slowness or difficulty in walking.In most people the presenting symptom of the disease is tremor, which usually begins on one side of the body (unilaterally) in the hand or arm. The tremor usually occurs at rest and decreases when the affected part is being used. It usually increases during times of stress or heightened emotion and decreases during sleep.
Stiffness or rigidity of the muscles can also occur - this can be quite painful and can cause difficulty in performing many everyday movements. Walking may be slowed and it can be difficult to start to walk. A lack of co-ordination may also cause problems.
Other symptoms include difficulties with balance, speech and writing and sometimes a lack of facial expression, altered posture and tiredness.
Some people may also experience symptoms unrelated to movement, such as memory impairment, mood disorders, sleep difficulties, loss of smell, constipation and drooling.