Complementing the previous commenter's answer: this is true for professional or active amateur boxing where you get headshots on a regular basis. This does not mean that anyone who decides to engage in percussion martial arts in their free time is a parkinson player in the terminal stage. At least for the first year, this person will not fight with anyone at all (if he studies from scratch): he will be taught how to get up in a stance correctly, move around, redistribute weight, then he will practice air strikes, shadow boxing, various practices (for example, did not squint when he took the hit). If the coach is not kicked out, of course, otherwise anything can happen.
Great physical activity does not have a negative impact on mental abilities. Moderate and regular, on the contrary, can contribute to their improvement. Boxing is an exception. Since the author chose a photo of a boxer as the cover of the question, I cannot fail to mention such a condition as dementia pugilistica - boxers' dementia. Since athletes in this sport have to endure frequent and strong blows to the head, over time, atrophy of brain neurons develops, which leads to a decrease in intelligence, memory, emotional instability.