Parkinson's disease is what is called a progressive neurological condition, meaning it affects the brain and gradually gets worse.
It mainly affects people over the age of sixty, although it can develop in much younger individuals, a fact highlighted by the actor Michael J Fox's continuing battle against the disease.
Parkinson's is believed to be caused by a lack of the brain chemical dopamine, the substance required for normal movement. The disease adversely affects the nerves in the brain that creates this chemical.
The common symptoms of Parkinson's are shaking (particularly the hands), stiffness and a general slowing down of body movement.
As yet there is no cure for the disease but great strides are currently being and hopes are high for a major breakthrough in the coming years.
At the moment, treatment for Parkinson's largely involves drugs designed to to refill the lost dopamine levels in the brain. However, finding the correct balance is hugely problematic because of the side effects of such medication which can include severe nausea and frequent hallucinations.