Jake Paul says he is suffering from mood swings, memory loss, and slurred speech less than two years into his boxing career.
The 24-year-old YouTuber opened up about his symptoms in a new interview with journalist Graham Bensinger ahead of his fight against Tyron Woodley.
"I notice it in conversations with like, with my girlfriend or friends, like, not remembering something that I should be able to remember that happened a couple days ago," he explained.
"Sometimes in my speech, where like every hundredth or two hundredth word, I'll mess up or, like, slur. Which I didn't do that before."
Watch Jake Paul's interview with Graham Bensinger here:The YouTube star-turned boxer claims he's endured anywhere between 20 and 30 concussions in his lifetime, though "it's really hard to say" exactly how many.
Some of the concussions came from playing football as a kid, he says, and taking "lots of hard hits," but many of them have come in the short time since he took up boxing professionally.
Repeated concussions and traumatic brain injuries can lead to CTE, or chronic traumatic encephalopathy, a rare and progressive degenerative brain condition.
According to Mayo Clinic, CTE symptoms include difficulty thinking, depression, impulsive behavior, short-term memory loss, and emotional instability. Irritability, aggression, speech difficulties, trouble swallowing, and vision problems may also be signs of the condition.
Before taking up boxing professionally, Paul recalls having his brain scanned. He says a doctor informed the YouTube star that he already was suffering from a lack of blood flow in "certain areas" of his brain due to the concussions he sustained while playing youth football.
Paul said he was told that one of the impacted areas is his frontal lobe. He returned for another brain scan one year later, "and it was worse," he added.
That's when doctors have advised him to quit boxing altogether, he told Bensinger.
"I think before, it was affecting me more at a rapid pace because I never took it easy," Paul explained. "I was always thrown in there with people who were way, way better than me until I started to slowly get to their level."
To ease his symptoms, Paul has admittedly ingested psychedelics such as toad venom.
"I've experimented with that and it's definitely helped out," he told Bensinger, citing "new research and science" he has discovered about the physical impacts of the substance.
Paul will square off against Tyron Woodley, 39, on Saturday, December 18, in a pay-per-view rematch of their August fight.