Two more retired football stars have pledged their brains to research.
Two-time Super Bowl champion Leonard Marshall and three-time Pro Bowl selection Matt Hasselbeck say they will donate their brains to the Concussion Legacy Foundation for research into chronic traumatic encephalopathy.
The announcements were made on Wednesday as part of the second annual Brain Trust conference, which is hosted by the Veterans Administration.
Marshall says he already has short-term memory loss and erratic behavior. The former New York Giants defensive lineman is 55. Hasselbeck's father, Don, was a teammate of Marshall's on the Giants and pledged his brain to the foundation in 2010.
More than 1,800 former athletes and military veterans have pledged to donate their brains to the Concussion Legacy Foundation for CTE research. The progressive degenerative brain disease has been linked to repeated head trauma.