(TNS) — In September, former Chiefs running back Larry Johnson tweeted some shocking news: he believes he has chronic traumatic encephalopathy (CTE).

The disease has been found in 99 percent of former NFL players who donated their brains after their deaths. Johnson talked recently with the Washington Post’s Kent Babb about why he believes he has CTE.

For starters, Johnson told Babb that he can’t remember two of the nine seasons he played in the NFL. Johnson, who was drafted in the first round by the Chiefs in 2003, played in Kansas City until his release in the 2009 season. Johnson also played for the Bengals, Washington and the Dolphins before leaving the NFL after the 2011 season.

It wasn’t clear if Johnson had forgotten his time with the Chiefs, although he played 75 of his 85 career games with Kansas City.

Johnson talked to the Post about wanting to make sure his 7-year-old daughter, Jaylen, will know about his success on the field when she is an adult. He holds Chiefs records for most rushing attempts in a game, season and career, and has the most rushing yards in consecutive seasons (3,539 in 2005-06). Johnson is third on the Chiefs’ career rushing list.

The Post story says that a fear of forgetting more of his playing history is why Johnson has started “making video compilations of his football highlights, in part as reminders to himself that he was involved in them — but also, when she’s ready, as a time capsule for Jaylen. …

“The project became urgent a few months ago, after a particularly severe case of CTE was discovered in the brain of Aaron Hernandez. The former New England Patriots tight end, with a history of erratic and explosive behavior, was convicted of first-degree murder in 2015 before hanging himself in his prison cell in April.”

“I could be Aaron Hernandez,” Johnson told Babb.

Johnson also revealed in the Washington Post story that he has type-1 bipolar disorder, which he blamed on head injuries while playing football.

During his time with the Chiefs, Johnson’s phenomenal success on the field was nearly matched by trouble off it.

In 2003, Johnson was charged with aggravated assault and misdemeanor battery for allegedly brandishing a gun, but those charges were dropped after he completed a domestic-violence diversion agreement. In 2008, Johnson twice was arrested on assault charges but pleaded guilty to two counts of disturbing the peace and was sentenced to two years of probation.

Johnson found more trouble when he made fun of then-coach Todd Haley’s lack of playing experience in 2009 and later for using a gay slur. After a two-week suspendsion, he was released.

In May, Johnson opened up about his off-the-field troubles and said, “I basically ran amok in Kansas City.”

“Certain things happen in your life,” Johnson told Babb, “that you just can’t come back from.”

Johnson also talked extensively about battling the violent urges he has today.

On Wednesday morning, Johnson tweeted about the story that he “didn’t do this for me 2 shift blame on any of my indiscretion’s. I wanted 2 show the children I work with N former players at every level high N low that it’s ok 2 be vulnerable N most of all accountable. A child’s love saves me, that child happens 2 be my own.”