Dr. Ann McKee, a neuropathologist, has examined the brains of 202 deceased football players. A broad survey of her findings was published on Tuesday in The Journal of the American Medical Association.
Of the 202 players, 111 of them played in the N.F.L. — and 110 of those were found to have chronic traumatic encephalopathy, or C.T.E., the degenerative disease believed to be caused by repeated blows to the head.