What is chronic traumatic encephalopathy, or C.T.E.?

A neuropathologist has examined the brains of 111 N.F.L. players — and 110 were found to have C.T.E., the degenerative disease linked to repeated blows to the head.

https://www.nytimes.com/interactive/2017/07/25/sports/football/nfl-cte.html?smid=tw-nytsports&smtyp=cur