Regarding CTE and youth football. I coached my sons teams throughout pop warner. Its a little different now in the older divisions (not so much by weight but by age) , but back then it was a combination of weight and age, for instance we had older/lighters - kids that were older but undersized weight wise- ostensibly to protect them - but those kids were the most "football aware" . 99% of the kids at young ages, i'd say up to puberty, aren't playing the game where they are exposing their head in contact - they are more dancing than hitting. unfortunately there is that 1% , that i call football aware that are the kids who aren't afraid of the contact and , too often, lead with their head no matter how much you try and coach that out of them.
Those are the kids that are the most accomplished in the game and go on to play beyond high school. so yes those kids are exposed to years of head contact and where CTE can become an issue and its mostly when they run into like minded kids on other teams. i coached a couple of kids who had concussion issues in PW, so much so that we had to end their seasons. One ended up as the gatorade player of the year in Ri his senior year and went on to play at Bryant and made it to an NFL camp - so basically 15 years or football, i worry about him. Another continued with his concussion issues as a HS freshman and quit football. My point is for most kids playing youth football the exposure minimal, so if the kid wants to play let them play, but there are some kids , and you can see it early, who are headed in the wrong direction and they are usually the ones that play for an extended period.
Personally i played organized football six years from puberty through senior year in HS with what i believe was only one concussion without any lasting effects