...were based on exposure to repetitive head trauma rather than on clinical signs of brain trauma...
So how the heck was exposure to "head trauma" quantified? By whom? Players, doctors, family members? And what exactly constitutes head trauma ? Every bump on the head? Concussions only?
It’s a complicated subject for a clinical test because head injuries aren’t all the same. Football helmets were originally designed to protect against skull fractures, which are impact injuries to the head. A concussion, on the other hand, is caused by sudden, rapid movements of the head ... which aren’t necessarily prevented by enhanced head protection.