In his column, Will pointed to three former NFL players — Ray Easterling, Dave Duerson and Junior Seau — who committed suicide in the past two years. Brain tissue from Easterling and Duerson, Will notes, showed evidence of chronic traumatic encephalopathy. Seau’s brain tissue is being studied. The National Institute of Neurological Disorders and Stroke says CTE is caused “by repetitive blows to the head over a long period of time.”

The NIOSH study indicated that NFL alumni are less likely to commit suicide than others. Whereas 21.8 men would have killed themselves in the general population, only nine NFL veterans did.

But the question about brain injury among NFL players is a serious one. In the NIOSH study, 12 of 3,439 players died of diseases of the nervous system and sense organs. Only 9.7 men in the general population would have died of these causes. NIOSH soon will complete a study examining in greater detail the mortality in this small group of former NFL players.