[BostonCard]

I agree on all counts.  In an ideal study, you would want to compare a random sampling of exposed (football players') brains to non-exposed (non-football players' brains), but even then it wouldn't be perfect because it wouldn't account for the possibility that football players might be more likely to engage in behavior (e.g. Tonga Juice drinking) than non-football players.  You would also ideally like to show a dose-response (playing more football increased your likelihood of having CTE).  Finally, you would want clinical correlates to the pathological findings.

Establishing causation in the absence of a randomized placebo-controlled study is tricky.

BC

[BostonCard]

I agree on all counts.  In an ideal study, you would want to compare a random sampling of exposed (football players') brains to non-exposed (non-football players' brains), but even then it wouldn't be perfect because it wouldn't account for the possibility that football players might be more likely to engage in behavior (e.g. Tonga Juice drinking) than non-football players.  You would also ideally like to show a dose-response (playing more football increased your likelihood of having CTE).  Finally, you would want clinical correlates to the pathological findings.

Establishing causation in the absence of a randomized placebo-controlled study is tricky.

BC