Chronic traumatic encephalopathy, the neurodegenerative disease linked to football, was successfully identified for the first time in the brain of a living person, Dr. Bennet Omalu told ESPN Thursday. Omalu was recently portrayed by Will Smith in the film "Concussion."

Omalu, the neuropathologist who first discovered CTE in the brain of a former football player, said results of testing done on former Vikings linebacker Fred McNeill while he was alive were "very similar" to what was found in an autopsy after McNeill's November 2015 death.

McNeill was a participant in a UCLA study of 14 former NFL players to develop methods of identifying CTE in people while they are alive. ESPN reported McNeill "is the first ex-NFL player in the study to have died," therefore the first in the study to have preliminary test results confirmed post-mortem.

CTE is believed to be caused by repetitive sub-concussive hits, the bread and butter of the game of football. Symptoms can include memory loss, mood impairment, and dementia. The disease has been found in a number of well-known former NFL players, including Junior Seau, Mike Webster, Frank Gifford, and most recently, Ken Stabler.

McNeill played for 11 seasons on the offensive line, where players are exposed to the highest rate of hits.

The UCLA study was conducted using a "brain-imaging tool they had developed previously for assessing neurological changes associated with Alzheimer's disease," according to a 2013 press release.

"[Researchers] employed a chemical marker they created called FDDNP, which binds to deposits of amyloid beta 'plaques' and neurofibrillary tau 'tangles' — the hallmarks of Alzheimer's — which they then viewed using a positron emission tomography (PET) scan, providing a 'window into the brain,'" the statement read. "With this method, researchers are able to pinpoint where in the brain these abnormal proteins accumulate."

McNeill became involved with the UCLA study after his wife, Tia, reached out to Dr. Omalu with concerns about her husband's changing personality, according to CNN. Upon examination, Omalu told the family he observed a buildup of tau proteins consistent with CTE.

A verified process to diagnose CTE in living people has enormous implications for football and the understanding of its link to the disease. Omalu is currently in the Bay Area, where Super Bowl 50 will be held on Sunday, and will be speaking at a public event Thursday night.