Former Minnesota Vikings quarterback and Pro Football Hall of Fame member Brett Favre, 54, announced at a congressional hearing Tuesday that he has recently been diagnosed with Parkinson’s disease.

Other pro athletes like legendary boxer Muhammad Ali and Major League Baseball star Kirk Gibson have battled the degenerative disease. Here are some details about it.

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

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

There currently isn’t a cure for Parkinson’s disease. However, medicines and even some surgeries can help control patients’ symptoms, according to Mayo Clinic.

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

According to a study done by Fox’s foundation and Boston University in 2023, playing football can increase the risk of Parkinson’s or related symptoms, including among people who only played at the amateur level. The study also said the longer someone plays football, the greater the risk of Parkinson’s.

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