On Friday, June 3, 2016, after a long battle with Parkinson’s disease, boxing legend Muhammad Ali, age 74, died. But in the aftermath of his death, the neurological illness that killed him continues to trigger questions. Was Ali’s Parkinson’s caused by the former champion absorbing too many punches? Or did genetic factors drive the disease that led to his demise? A CNN report explored the facts.


In general, Parkinson’s disease is a progressive disorder of the nervous system that causes neurons to die. When these nerve cells expire, they leave the brain deficient in a chemical called dopamine. Parkinson’s slowly destroys a person’s motor skills and ability to speak coherently. Early symptoms of the disease include small tremors in the hands or muscles, slowness of movement, a loss of balance and slurred speech. Today, the condition affects approximately 1 million Americans.


When Ali was diagnosed with Parkinson’s in 1984, he’d been retired for three years from his incredible boxing career, during which he earned a gold medal and the heavyweight champion three times in the 1960s and 1970s. But Ali’s Parkinson’s disease wasn’t caused by the physical trauma he suffered throughout his career; the culprit was genetics, according to his doctors.


Still, researchers don’t know exactly what causes brain cells to deteriorate in patients with Parkinson’s. Some scientists think developing this disease may be connected with mutations of the LRRK2 gene, which can be passed down from generation to generation. And although recent studies have also linked specific environmental toxins with Parkinson’s, a relationship between the disease and this possible trigger hasn’t yet been proved.


Currently, Parkinson’s disease cannot be cured, but the illness can be managed with certain medications. One drug, called levodopa, helps the brains of people with Parkinson’s make more dopamine. Deep brain stimulation that involves implanting electrodes into the brain may also be used to help control problems with movement. In addition, some patients use physical therapies, such as tai chi, to cope with symptoms of the illness.


Despite the debilitating disease, Ali fought back against Parkinson’s any way he could. In 1997, he and his wife co-founded the Muhammad Ali Parkinson Center in Phoenix to provide comprehensive care for those living with the disease. The center has also funded more than 40 projects to help solve, treat and end Parkinson’s disease in the future.


For more information about Parkinson’s disease, click here.