ROBERT AZMITIA/Associated Press

Former NFL running back Charlie Garner, who says he suffered at least 12 concussions per season during his football career, said doctors believe he's dealing with the early stages of Chronic Traumatic Encephalopathy.

"I don't have all my faculties anymore," Garner told Pat Yasinskas of Sporting News. "I can't remember things. When I go to the mall or grocery store, I have to take one of my kids with me to remember where the car is parked. I have trouble remembering conversations I had five minutes ago. Bright lights bother me. I just don't feel right all the time."

Garner, 45, rushed for 7,097 yards and 39 touchdowns over an 11-year NFL career. He played for the Philadelphia Eagles, San Francisco 49ers, Oakland Raiders and Tampa Bay Buccaneers.

A former girlfriend of Garner said he deals with violent mood swings. While she said he was never physically abusive, he could turn verbally abusive almost instantaneously.

"He was a pussycat one minute and a lion the next," the ex-girlfriend said. "You just never knew when the volcano would erupt."

As his symptoms worsened, Garner began learning more about what is causing his issues. He learned things like minor hits—the so-called "getting your bell rung"—and other standard actions could have caused undiagnosed concussions.

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"He explained that even minor collisions could cause the brain to rattle against the skull," Garner said of his doctor who explained CTE. "When I thought about that, I realized I probably had at least a dozen concussions a year and played through them. You do the math. At least a dozen concussions a year over 11 years. No matter how you look at it, that's a lot."

Garner was part of the contingent of former players who sued the NFL regarding their handling of information on concussions. A settlement will pay players $1 billion and will be distributed based on the severity of their symptoms.

"Football gave me a good lifestyle for me and my family," Garner said. "But I might end up paying a big price for it. Other people already have paid a big price for it. People ask me all the time if I would do it all over again if I knew more about concussions. I say yes, but I would do it as a defensive back because I wouldn't have taken so many hits."

Garner said he would not prevent his son from playing tackle football if he chooses to do so in the future. He would, however, urge him to play defensive back or a less contact-intensive position.