Junior Seau, one of the NFL's best and fiercest players for two decades, suffered from a degenerative brain disease often associated with repeated blows to the head when he committed suicide last May, the National Institutes of Health said in a study released Thursday.
The NIH, based in Bethesda, Md., said Seau's brain revealed abnormalities consistent with chronic traumatic encephalopathy or CTE. It said that the study included unidentified brains, one of which was Seau's, and that the findings on Seau were similar to autopsies of people "with exposure to repetitive head injuries."
Seau's family requested the analysis of his brain.
The star linebacker played for 20 NFL seasons with San Diego, Miami and New England before retiring in 2009. He died of a self-inflicted shotgun wound.
He joins a list of several dozen football players who were found to have CTE. Boston University's center for study of the disease reported last month that 34 former pro players and nine who played only college football suffered from CTE.
"I was not surprised after learning a little about CTE that he had it," Seau's 23-year-old son Tyler said. "He did play so many years at that level. I was more just kind of angry I didn't do something more and have the awareness to help him more, and now it is too late.
"I don't think any of us were aware of the side effects that could be going on with head trauma until he passed away. We didn't know his behavior was from head trauma."
That behavior, according to Tyler Seau and Junior's ex-wife Gina, included wild mood swings, irrationality, forgetfulness, insomnia and depression.
"He emotionally detached himself and would kind of 'go away' for a little bit," Tyler Seau said. "And then the depression and things like that. It started to progressively get worse."
The NFL faces lawsuits by thousands of former players who say the league withheld information on the harmful effects concussions. According to an AP review of 175 lawsuits, 3,818 players have sued. At least 26 Hall of Famer members are among the players who have done so.
Seau is not the first former NFL player who killed himself, then was found to have CTE. Dave Duerson and Ray Easterling are the others.
Dr. Russell Lonser, who oversaw the study, said Seau's brain was "independently evaluated by multiple experts, in a blind fashion."
"We had the opportunity to get multiple experts involved in a way they wouldn't be able to directly identify his tissue even if they knew he was one of the individuals studied," he said.
The National Football League, in an email to the AP, said: "We appreciate the Seau family's cooperation with the National Institutes of Health. The finding underscores the recognized need for additional research to accelerate a fuller understanding of CTE.
"The NFL, both directly and in partnership with the NIH, Centers for Disease Control and other leading organizations, is committed to supporting a wide range of independent medical and scientific research that will both address CTE and promote the long-term health and safety of athletes at all levels."
NFL teams have given a $30 million research grant to the NIH.
"You can't deny it exists," Gina Seau said, "and it is hard to deny there is a link between head trauma and CTE. There's such strong evidence correlating head trauma and collisions and CTE."