Brett Favre, 54, a former Minnesota Vikings quarterback and Pro Football Hall of Fame inductee, announced during a congressional hearing Tuesday that he had recently been diagnosed with Parkinson’s disease.

Other professional athletes such as legendary boxer Muhammad Ali and Baseball Hall of Famer Kirk Gibson have battled the degenerative disease. Here are some more details about it.

According to the Mayo Clinic, Parkinson’s disease affects the movement of the nervous system, causing tremors, slowed movements and balance problems, among other symptoms. The disease gets worse over time and is more common in men over 50.

The cause of the disease is unknown, but genes and environmental factors may increase the risk of Parkinson’s disease, according to the Mayo Clinic.

There is currently no cure for Parkinson’s disease. However, medications and even some surgeries can help control patients’ symptoms, according to the Mayo Clinic.

Many charities, such as the Michael J. Fox Foundation for Parkinson’s Research, have donated money to research for a cure.

According to a 2023 study conducted by Fox’s Foundation and Boston University, playing soccer may increase the risk of Parkinson’s or related symptoms, even in people who only played at an amateur level. The study also said that the longer a person plays soccer, the greater the risk of Parkinson’s.

According to the Mayo Clinic, football has long been linked to other neurological conditions, such as chronic traumatic encephalopathy (CTE), which is caused by repeated injuries to the head.