Brett Favre announced his diagnosis on Tuesday. Here’s what we know about the disease and its relationship to head injuries.

More than a decade after retiring from football, Brett Favre says he has Parkinson’s disease. Favre told a congressional hearing Tuesday that he had been recently diagnosed. There are nearly 90,000 new Parkinson’s cases each year in the U.S., according to the Parkinson’s Foundation.

Legendary quarterback Brett Favre says he was “recently diagnosed with Parkinson’s disease” while speaking at a congressional hearing on Tuesday. Favre, 54, is testifying at a hearing of the House Ways and Means Committee examining welfare reform,