Karras is probably most familiar to people as an actor, with his two most famous roles being the father on the sitcom "Webster" and Mongo, the guy who punched out a horse in the classic Mel Brooks movie, "Blazing Saddles."
His wife, actress Susan Clark, said earlier this year that her husband couldn't drive and could no longer remember recipes for some of his favorite Italian and Greek dishes he used to cook.
Clark, who played the wife of Karras' character on “Webster,” has said he was formally diagnosed with dementia several years ago and has had symptoms for more than a dozen years.
Karras played his entire NFL career with the Lions before retiring in 1970 at age 35. He made the Pro Bowl four times and missed the 1963 season when he was suspended by NFL Commissioner Pete Rozelle in a gambling probe. Karras was recognized by the Pro Football Hall of Fame as a defensive tackle on the All-Decade Team of the 1960s.
“We know Alex first and foremost as one of the cornerstones to our Fearsome Foursome defensive line of the 1960s and also as one of the greatest defensive linemen to ever play in the NFL,” Lewand said. “Many others across the country came to know Alex as an accomplished actor and as an announcer during the early years of 'Monday Night Football.'
“We join his legions of fans from both sports and entertainment in prayer and support for Alex, his wife Susan and his entire family during this most difficult time.”
The Associated Press contributed to this report.