“The brain is made up of 86 billion neurons,” Nowinski said in a telephone interview. “We are talking here and there about a little microscopic lesions. The location of the lesions and how your brain is wired will likely have more of an impact than the staging. A lesion of one millimeter in the other direction could make the difference between normal behavior and impaired behavior.

Step 1 is the first sign of CTE Lesions are mostly found in the frontal lobe and symptoms often include mild memory loss. In 2nd step, the lesions have spread to the adjacent cortex, continuing their assault on memory. Damage to the frontal lobe, Nowinski said, is well known to be associated with problems with concentration, cognition and impulse control. Examination of Adams’ brain, which turned out to have stage 2, indicated an unusually severe diagnosis for a person in their 30s, similar to that found in Hernandez, in whom McKee diagnosed Step 3, in which the lesions have invaded the median temporal lobe, affecting the hippocampus and amygdala, and causing impulsive and violent reactions; paranoia; and erosion of memory.

In Step 4, when CTE has spread to multiple parts of the brain, Nowinski said, the vast majority of people have been clinically diagnosed with dementia. He said 13 years tend to pass between stages, and people over 60 with CTE are almost always in stage 3 or 4.

What was CTE’s impact on the NFL?

Hall of Fame center Mike Webster was the first NFL player to have a CTE, the result being published in a science journal three years after his death in 2002. Over 315 former players, including Ken Stabler and Frank Gifford, were posthumously diagnosed by Boston University CTE researchers announced in a 2019 study that prey on soccer players doubled their risk of developing the worst forms of CTE for every 5.3 years they played.

For many years, the NFL denied any connection between long-term brain damage and blows to the head until it faced overwhelming scientific evidence. When a class action lawsuit by former players surfaced, the league acknowledged the connection and agreed to a settlement of around $ 1 billion; the NFL has since agreed to stop using race-based methods in assessing dementia claims that denied black gamers benefits potentially worth hundreds of thousands of dollars.

In response to the increasing prevalence of CTE, the NFL has developed intensive protocols for players who have, or are showing signs of, a head injury. The league has installed a head injury observer in the press stands of all games; doctors and specialists in neurotraumatology on the fringes; and experts in neurocognitive testing in the locker room. The league has also tightened the rules against quarterbacks and players who lower their helmets to initiate contact.

The NFL has invested hundreds of millions of dollars in helmet and concussion research, and even ran a $ 3 million grant competition aimed at improving helmet performance and safety. According to the league, 99.9% of players wore what he considered a “best performing helmet” last season, and it is hoped that position specific helmets will be introduced soon.