Five brain specialists at the National Institutes of Health have determined that Junior Seau, the former superstar linebacker in the NFL who killed himself in May, tested positive for chronic traumatic encephalopathy (CTE), a brain disease linked to dementia, memory loss and depression. CTE – caused at least in part by repeated head trauma – has long been associated with boxers but, since 2005, has been found in 50 former football players.

Seau’s ex-wife Gina told ESPN her husband endured “a lot of head-to-head collisions over the course of 20 years of playing in the NFL. And that it gradually, you know, developed the deterioration of his brain and his ability to think logically.”

Seau used a .357 Magnum to shoot himself in the heart on May 2, leading the media to jump to the convenient narrative that a long career in a violent sport contributed to his death. While the science hasn’t yet caught up to that assumption, more studies are showing a higher tendency among football players to be at an increased risk for mental problems later in their lives.

Part of the confusion comes from what some call a widespread misdiagnosing of concussions. Doctors now encourage young athletes to step away from the field if they’re dazed, a policy that flies in the face of old-school coaches and athletes who say they can just “shake it off.” Seau was never described as having a concussion.

"I think it's important for everyone to know that Junior did indeed suffer from CTE," Gina Seau said. "It's important that we take steps to help these players. We certainly don't want to see anything like this happen again to any of our athletes."

Seau’s son Tyler, 23, was contacted within hours of his father’s death by researchers hoping to examine Seau’s brain for signs of severe head trauma. Tyler said his dad had changed in what would become the latter years of his life, suffering from frequent mood swings, depression, insomnia and forgetfulness.

"He would sometimes lose his temper," Tyler said. "He would get irritable over very small things. And he would take it out on not just myself but also other people that he was close to. And I didn't understand why."

Recent years have seen an uptick in athletes who take their own lives, report symptoms of dementia or act out in a way that’s unlike their own personality. Skeptics point to the possibility that ex-athletes were forced to deal with chronic pain, drug addiction, a lack of funds or the hurt ego that comes with stepping away from professional sports.

"The difference with Junior ... from an emotional standpoint (was) how detached he became emotionally," Gina Seau said. "It was so obvious to me because early, many, many years ago, he used to be such a phenomenal communicator. If there was a problem in any relationship, whether it was between us or a relationship with one of his coaches or teammates or somewhere in the business world, he would sit down and talk about it."