When former NFL star Junior Seau committed suicide last year, he had a brain disease linked to repeated blows to the head. That's according to the National Institutes of Health.

Seau is the latest prominent player to suffer from a brain disease called Chronic Traumatic Encephalopathy, or CTE.  CTE is connected to athletes who get hit in the head a lot during their playing careers. 

Last spring, Seau committed suicide by shooting himself in the chest.  Many believe he used that method so that doctors could study his brain.

The NFL players’ union responded to the NIH with a statement that reads in part:

"The only way we can improve the safety of players, restore the confidence of our fans and secure the future of our game is to insist on the same quality of medical care, informed consent and ethical standards that we expect for ourselves and for our family members."

Seau's son told ABC News that the risks his father took during his NFL career were, "not worth it for me to not have a dad."