Think of Muhammed Ali. However, the cause of PD is still unknown and being researched.

Yes & that info seems to indicate that it is a definite possibility.

My husband was in a car accident when a woman turned into oncoming traffic. His vehicle was written off and he hit his head and does not remember the impact or a period of time after. Parkinson's type symptoms began shortly after - slowed movement, stiffness, pain in his shoulder and back, speech issues etc. He went for a sleep study to investigate Apnea and poor quality sleep and they suggested he see a Neurologist. The neurologist confirmed a Parkinson's diagnosis at the age of 46.
It may have already been brewing but symptoms appeared soon after so I have always wondered if there was a connection? My husband is sure of it.

Boxing ,football describe cases of parkinsonismm

Yes, me too