Jackass Forever star Johnny Knoxville says he suffered serious brain damage while filming the upcoming movie. Knoxville detailed the injury during an interview with Howard Stern, earlier this week.

“My cognitive abilities were in steep decline after that hit,” Knoxville admitted. “No one in my family is happy with the stunts.”

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“The bull hit was the worst hit I’ve ever taken from a bull or maybe period. I remember taking some tests. The neurosurgeon said, ‘Do you have trouble paying attention right now?’ I said, ‘Yeah, why?’ He goes, ‘Because you scored a 17 on [your attention].’ That’s out of 100.”

In addition to his brain injury, Knoxville says the bull stunt landed him a broken wrist and broken ribs.

“I can’t take any more hits to the head…. My brain was just playing tricks on me. I got really depressed and over-focused on things. I did have to start medication for the first time in my life. It completely turned me around — that and doing therapy. It was a really hard recovery from this last injury but I’m great now. I feel like I’m the healthiest I’ve ever been.”

Jackass Forever arrives in theaters on Febuary 4.

Check out Knoxville’s discussion with Stern below.