Description

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Parkinson's disease is the second most common neurodegenerative disease after Alzheimer. According to the United Nations, at least six million people are affected by PD worldwide. (2). Parkinson's disease occurs when certain neurons of the brain, mostly in the substantia nigra die or become impaired. The symptoms of Parkinson's disease result from the loss of these dopamine-secreting (dopaminergic) cells and subsequent loss of melanin, secreted by the same cells, in the pars compacta region of the substantia nigra (also known as black substance). This leads to inhibition of the direct pathway of movement and activation of the indirect pathway of movement. Since the direct pathway facilitates movement and the indirect pathway inhibits movement, the loss of these cells leads to a hypokinetic movement disorder. The lack of dopamine results in an excessive inhibition of the thalamus, leading to hypokinesia (3).