Mark Duper joined a list of former NFL players who have tested positive for Chronic Traumatic Encephalopathy (CTE) when he learned of the diagnosis on Friday afternoon.
Duper, a three-time Pro Bowl wide receiver for the Miami Dolphins, was tested at UCLA and found to have mild cognitive impairment, he told CBSSports.com.
The 54-year-old Duper is the fourth ex-NFL player this week to show signs of CTE and the ninth living player known to have been diagnosed. Hall of Famers Tony Dorsett and Joe DeLamielleure and former All-Pro defensive lineman Leonard Marshall also are affected, ESPN reported.
CTE is related to head trauma and linked to dementia and depression. Former San Diego Chargers All-Pro linebacker Junior Seau's brain was found to have a protein that damages cells after he committed suicide last year.
Duper said he has noticed warning signs in recent years that included bouts with anger and forgetfulness.
"It was shocking," Duper told ESPN's Outside the Lines. "I hoped nothing was wrong. I've had memory things where I would go to the store and forget what I went for. And I have emotional swings and panic attacks."
In 11 seasons, Duper had 511 receptions for 8,869 yards and 59 touchdowns. He said he wouldn't trade his career for anything.
"I don't have any regrets about playing," Duper said. "I made a good living off football and I'm still making a living off it. You can't regret something you enjoyed, something you love and I loved football."
Duper is hoping the research helps younger players.
"I'm thinking back on my life and where I am going with this," he said. "I have to deal with it and make the best of it. It does make me think of the future and how things are gonna change."
Duper plans to carry on with his life. He soon will begin oxygen therapy treatments.
"Hopefully, this can put things into perspective for younger players," Duper said. "The rules are changing--the rules have changed. Players should get themselves tested."