Transcript for Former NFL star claims he's living with CTE
football injuries after another tough hit in the NFL overnight. There you see Brandon Williams from the colts, helmet on helmet hit taken off the field with a concussion and now former NFL star Larry Johnson speaking out in an ABC news exclusive. Johnson is 38, convinced he's living with cte as he battles memory loss, anxiety and suicide impulses. Linsey Davis sat down with him and joins us now. He was a first round draft pick in 2003 and today he says there are two entire NFL seasons he simply doesn't remember. He says he doesn't blame the NFL but Johnson says it's time to change the way the game is played because he believes the game has changed him. He played the game with a rage that made him great. To the 47. Reporter: A 2002 Heisman trophy finalist at Penn state and two-time pro bowler. In 2006 playing for the Kansas City chiefs Larry Johnson carried the ball 416 types, an NFL record. Thank you for talking with us but the 38-year-old former NFL running back now believes he suffers from cte, chronic traumatic encephalopathy. Why do you believe you have cte. I get light headaches every now and again and my anxiety levels are off the chart. Sometimes I have to retreat back to my own place because the anxiety makes my heart beat faster. Reporter: He is convinced his many symptoms including erratic mood swings all point to cte. You've been diagnosed with bipolar disorder. Why not attribute to them. They don't have anything to do with my headaches or why I'm sensitive to light or noise. Reporter: He describes destructive impulses and in some cases actions. Johnson has been arrested six times, several times for assaulting women. In 2009 he was waived by the chiefs after being suspended for conduct detrimental to the club. Rock bottom is almost losing custody of your daughter, not coming home at night. Don't know where you are. I was letting life drag me along and hopefully someone would put me out of my misery. Reporter: A pattern he says is not all that unlike Aaron Hernandez, the former new England patriot who committed suicide in his jail cell while serving a life sentence for murder and found to have the most severe case of cte in anyone his age. This doctor says while we can't diagnose cte while someone is still alive, we can suspect cte based on their symptoms and if they've been exposed to repetitive head trauma. It can be very difficult to distinguish between mental health issues and cte symptoms and I would say in this particular situation it's close to impossible. Have you ever had a concussion? I never really had a concussion but the repeated head trauma I received since 9 all adds up. Reporter: He distinctly remembers being 9 years old playing his very first game of tackle football. The very first kickoff turn and I got tunnel vision and it was like a white light and that was it. I laid out on the field. They tried to get me to go back in the game and I said I don't want to go back. If you go back to your 9-year-o 9-year-old self do you walk away forever. No, it's ingrained in me. Reporter: It's children he credits with helping him now, an organization called motivational edge which uses art to help children express emotional trauma. We allow them to be themselves and create a safe space for them to be themselves. If he does have a son he'll let him play football but not tackle until high school and asked if he would play football all over again. He said without hesitation, yes, but he says he would play it differently. He feels there needs to be more education about how to hit, how thought to hit to avoid the head-jarring devastating blows and would juke more rather than tackle head on. Yeah, I played against him. He was a big, strong guy. He would come at you. I agree with him about education about tackling. There's a right way and wrong way to tackle. You don't lead with your head but some of my friends have had to retire because they've had concussion issue, all of them said they would play again. They would not change it. Interesting. Really interesting. Thank you, great piece.
This transcript has been automatically generated and may not be 100% accurate.