Very depressing news about football. A study looking at those who played football long-term (as a career in adulthood) found that for every year of playing tackle football (lots of pounding and repeated head collisions), a person's risk of developing chronic traumatic encephalopathy (CTE) increases by 30%. The researchers from the Boston Univ. School of Medicine arrived at this conclusion after looking at 266 deceased former amateur and professional football players.
What was different about this study was that they compared football players who did not develop CTE with those who did - so the researchers thought it was representative of career football players.
The study results make total sense, but are horrifying because of all the children in the US growing up and playing tackle football from a young age. Other studies find brain changes from just playing some semesters in high school or college or before the age of 12.