The brain disease chronic traumatic encephalopathy (CTE), linked to repeated hits to the head, can only be diagnosed after death via a brain autopsy. But many very-much-alive former professional football players believe they have it.

One third of former NFL players believe they have brain damage from football, study shows 02:19. With two Philadelphia Eagles players in concussion protocol after Sunday's game, t

Among former NFL athletes who volunteered to complete a questionnaire, 34.4% said they perceived they had CTE, according to Rachel Grashow, PhD, MS, of the Harvard T.H. Chan School of Public Health in Boston, and co-authors.

Far from the lime light of the football field, former NFL players are asking themselves a chilling question: do I have CTE? About a third of surveyed football players in a new study in the journal JAMA Neurology think they have CTE,

The degenerative brain disease can only be diagnosed after death. But hundreds of retired players reported symptoms linked to CTE, like depression, mood swings and suicidal thoughts.

Roughly one-third of former professional football players surveyed believe they have CTE, a study found. The brain disease is linked to repeated hits to the head.

CTE also reported having suicidal thoughts Approximately one-third of former football players believe they have a degenerative brain disease known as chronic traumatic encephalopathy (CTE), according to a new survey.

About 35% of 1,980 retired professional football players who participated in a survey said they believe they have CTE, Harvard University study finds.