…move. Their muscles stiffen and in severe cases people will feel locked in position. The condition progresses unpredictably, and leads to other problems such as difficulty sleeping and depression.
Ali began showing symptoms of the disease soon after retiring from the boxing ring in 1981. But his condition was not diagnosed until three years later, in 1984. By that stage he had developed tremors, his speech was slurred, and his body movements had become slow. Currently, Ali is unable to speak in public.
Other possible causes of PD include:
Toxins: Exposures to pesticides and herbicides have been linked to Parkinson’s disease. Though scientists haven’t yet determined the exact cause of Parkinson’s disease, it’s believed a combination of genetic and environmental factors are involved.
Viruses: In the early 1900s, people who came down with a form of the encephalitis virus became stuck in a trance-like state in which they couldn’t move or speak. When neurologist Dr. Oliver Sacks treated these people with levodopa, the same medication used to treat Parkinson’s, they briefly came “back to life.”
Head Trauma: Researchers have studied whether trauma to the head, such as what Ali experienced consistenly as a professional boxer, may play a role in the development of the disease.
Structural Problems: Strokes and hydrocephalus (fluid buildup in the brain) are two conditions that may lead to an increased risk of PD.
The Parkinson’s Foundation has more on living well with Parkinson’s Disease.