CTE Q&A: What happened to Tyler Hilinski, what can be done

The news that Tyler Hilinski, the Washington State quarterback who shot himself with a rifle in January and left a suicide note, was diagnosed with chronic traumatic encephalopathy this week left researchers again warning about the dangers of tackle football.

Hilinski, 21, was diagnosed with Stage 1 CTE, the earliest stage of the disease that has been linked to the repeated head trauma common in football and other contact sports. His parents told Sports Illustrated that doctors from the Mayo Clinic said his brain looked as if it had come from a much older man.

"Did football kill Tyler? ... I don't think so," his mother, Kym Hilinski, told SI. "Did he get CTE from football? Probably. Was that the only thing that attributed to his death? I don't know."

Here are some other questions and answers about the disease, and Hilinski's story:

WHAT IS CTE?

A degenerative brain disease known to cause violent moods, depression, dementia and other cognitive difficulties, CTE has been linked to the repeated hits to the head endured by football and hockey players, boxers and members of the military.

Researchers have found evidence that the severity of the symptoms is increased for those who sustained concussive or sub-concussive blows at a younger age.

HOW MANY CONCUSSIONS DID HILINSKI HAVE?

Hilinski's parents told SI of that a hit he took as a college freshman that "rocked him," and they noted changes in his behavior after it. But studies have shown that even those who remember just a few concussions probably sustained many more that were undiagnosed - often dismissed as "stingers" or "getting your bell rung."

Although quarterbacks can take fewer blows to the head than players in the open field, like running backs or receivers, many QBs were among those diagnosed with CTE in the most complete study of the disease in former football players . (Hilinski also played receiver, and SI reported that as a linebacker in youth football he was known as a hard hitter.)

Researchers have also found a link between CTE and hits not hard enough to cause a concussion, like those sustained by offensive linemen, or soccer players from heading the ball.

IS CTE COMMON IN PEOPLE THIS YOUNG?

It's not common, but there's a big caveat: CTE can only be diagnosed in an autopsy, so young brains are less frequently studied. Still, it has been found in people who died as young as 17, and many victims were in their early 20s.

Kyle Raarup, a Minnesota youth hockey and football player who killed himself at the age of 20, gave up sports at 14 because of post-concussion syndrome. He was found to have Stage 1 CTE.

DID CTE CAUSE HILINSKI'S SUICIDE?

It's not possible to blame CTE for any specific death; nor is it possible to link any blow to the head to an diagnosis of CTE. Researchers are still trying to figure out why some people get CTE while others don't; in general, the brains that are studied have been donated by those who saw disconcerting behavior.

According to Chris Nowinski, a founder of the Concussion Legacy Foundation, several dozen of the cases studied came to the brain bank as the result of suicide. "There's a well-known link between even a single concussion and the increased risk of suicide," he said.

WHAT CAN BE DONE?

Citing evidence that brain damage is more severe for those who began playing contact sports earlier, researchers have called for a ban on tackle football for children younger than 14. Five states - New York, New Jersey, Maryland, Illinois and California - are discussing such legislation.

Some colleges are moving away from hitting in practice; the Ivy League has banned it entirely. The NFL has also taken steps to limit contact outside of the games, while adopting other rules to minimize the danger of concussions like de-emphasizing kickoff returns.

Many sports have instituted concussion protocols designed to keep players who may have sustained a traumatic brain injury from returning to the game. Educational initiatives directed at players and coaches attempt to show the dangers of playing after a concussion.