Muhammad Ali was a legendary boxer who was born and raised in Louisville, Kentucky. He began training as an amateur boxer at age 12 and won a gold medal in the light heavyweight division at the 1960 Summer Olympics. He turned professional later that year and won the world heavyweight championship in 1964, defeating Sonny Liston in a major upset at age 22. He converted to Islam after 1961 and changed his name to Muhammad Ali. In 1966, Ali refused to be drafted into the military owing to his religious beliefs and ethical opposition to the Vietnam War and was found guilty of draft evasion and stripped of his boxing titles. He stayed out of prison while appealing the decision to the Supreme Court, where his conviction was overturned in 1971. He did not fight for nearly four years and lost a period of peak performance as an athlete.

After retiring from boxing, Ali was diagnosed with Parkinsons disease in 1984 after checking himself into Columbia Presbyterian Hospital. Parkinsons disease is a progressive disorder of the nervous system that affects movement. Alis disease course, from his late 30s until his death at age 74 years, was chronic and progressive. He manifested fatigue, hypophonia, and a classic Parkinson disease left-arm rest tremor, which was suppressed as he raised his left hand to steady his right arm in order to light the torch during the 1996 Olympic torch lighting ceremony. Ali underwent a series of single medical examinations during his professional career from 1981 to 1984 at Un... Postretirement from 1995 until his death, he received his neurological care largely at 1 institution, Emory University in Atlanta, Georgia. He also received local care at the Barrow Neurological Institute in Phoenix, Arizona.

Alis last fight was in 1981 against Trevor Berbick, and the study found he was already slurring his words three years prior to that. A study set to be released in 2023 determined Muhammad Ali displayed signs of slowed or slurred speech as much as a decade before he was diagnosed with Parkinsons disease. According to the study, Alis speaking rate slowed by 26 percent from the ages of 26 to 39. Jonathan Eig, author of the upcoming biography Ali: A Life was part of the study as well, and he found Alis speech slowed by 16 percent after a 1977 fight against Earnie Shavers that saw him absorb 266 punches. Eig concluded Alis speech would slowly rebound the further removed he got from fights but that irreparable damage was done.

Muhammad Ali passed away in 2016 at the age of 74 after battling Parkinsons disease for more than 30 years.