Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease affecting approximately 1% of the population older than 50 years. There is a worldwide increase in disease prevalence due to the increasing age of human populations. The disease is characterized by tremor, stiffness of the limbs and trunk, impaired balance and coordination, and slowing of movements, leading to immobility and frequent falls. Patients also sometimes develop other symptoms, including difficulty swallowing, disturbed sleep, and emotional problems. Parkinson's disease results from the loss of dopaminergic neurons in the substantia nigra region of the brain. The cause and mechanism of continued neuron cell death in the substantia nigra is currently unknown.