The Department of Veterans Affairs and Boston University researchers studying the effects of head injuries in football found evidence of chronic traumatic encephalopathy (CTE) in the brains of 87 of 91 deceased NFL players they tested, according to data provided to PBS' Frontline.
The study, which looked at 165 individuals who played football at various levels, including high school and the NFL, found CTE in 79 percent of its participants overall.
Offensive and defensive linemen made up 40 percent of the subjects who tested positive for CTE.
The Frontline story notes several important factors with the researchers' findings: "The disease can only be definitively identified posthumously. As such, many of the players who have donated their brains for testing suspected that they had the disease while still alive, leaving researchers with a skewed population to work with."
Dr. Ann McKee, chief of neuropathology at the VA Boston Healthcare System, called the findings consistent with previous research.
CTE is a degenerative brain disease which researchers say can cause many symptoms including rage, impulsivity, depression, confusion, memory loss and eventually advanced dementia.