Aaron Hernandez was a victim of the most severe form of chronic traumatic encephalopathy (CTE) discovered in someone his age, The Washington Post reports.

Doctors say the damage would have significantly affected his decision-making, cognition and judgement, researchers revealed on Thursday.

The findings were disclosed at a Boston University medical conference on Thursday.

Ann McKee is the head of BU’s CTE Center, one that’s been studying the disease for more than a decade. She referred to Hernandez’s brain as “one of the most significant contributions to our work” due to its pristine condition. CTE is caused by repetitive brain trauma that often comes with professional football playing.

Hernandez served as a former New England Patriots tight end. In April he committed suicide by hanging in a Massachusetts prison while serving a life sentence for Odin Lloyd’s 2013 murder.

According to doctors, Hernandez had Stage 3 CTE. Researchers usually see that stage in brains 46 and older, McKee said.

“In this age group, he’s clearly at the severe end of the spectrum,” McKee said. “There is a concern that we’re seeing accelerated disease in young athletes. Whether or not that’s because they’re playing more aggressively or if they’re starting at younger ages, we don’t know. But we are seeing ravages of this disease, in this specific example, of a young person.”