Please help me? what is parkinson's disease?

Parkinson's: Parkinson's disease is a brain degenerative disease is caused by depletion of Dopamine from small structures in the brain, Dopamine is responsible to maintain normal movements in the body, pd usually is a degenerative disease affects old age people above 60 years old, clinically the patient will have rest tremors, rigidity, and slow gait, usually is treated by replacing Dopamine by oral medication.