The mitochondria are the tiny factories found in every cell. Their principal role is to produce Adenosine triphosphate (ATP) which is considered to be the energy currency of life. It is the high-energy molecule that stores the energy we need to do just about everything we do.
Our bodies start failing and we suffer chronic disease when our bodies have a deficit of ATP.
Aging is a consequence of mitochondria dysfunction, ie not producing sufficient ATP. The same applies to Parkinson’s.