muhammad ali | Kaitlyn Roland

In 1984, Muhammad Ali was a 42 years old former boxing champion who recently had to figure out how to live with his tremors, slurred speech and slow movements. He was diagnosed with Parkinson’s disease.

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: Ali 1980 (only 1yr prior to appearance of PD signs, 4 yrs before diagnosis)

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Ali fought late into his life; and especially his last two fights, Holmes (above) and Berbick, left him battered and bruised… to say the least.

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There are many people that believe Ali would have developed PD even if he lived a life as a quiet librarian, since the evidence linking boxing-related head trauma to development of PD is still controversial.

However, there’s another group that believe in a definitive cause-and-effect relationship.

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In 2006, study shows an association between prior head injury with loss of consciousness and PD (odds ratio= 3.8; 95% confidence interval, 1.3–11; p = 0.014) in twins, especially monozygotic (Goldman et al. Annals Neurology, 2006). Risk was increased with subsequent head injuries and/or hospitalization.

Puerto Rico's Arroyo twin boxers (2008)

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Another case-controlled study examined environmental risk of PD. This study found that head injury (OR=6.23) that occurred on average 37yrs prior to diagnosis was the strongest risk-factor for PD… Though you have to keep-in-mind people have a hard time remembering these events or may attach greater significance to them in hindsight, i.e.”recall bias”.