A former NFL lineman from Pennsylvania who killed himself at 25 had a brain disease that has been linked to repeated blows to the head, researchers confirmed Wednesday.

Adrian Robinson Jr.'s diagnosis of chronic traumatic encephalopathy was confirmed through officials at a brain bank at Boston University.

Family lawyer Ben Andreozzi said that Robinson had several concussions during two seasons in the league.

Robinson, of Harrisburg, played for Temple University in Philadelphia before playing for Pittsburgh, Denver and San Diego.

"He went from being one of the nicest guys you'd ever want to talk to, to having a darker edge at times," Andreozzi said. "The family started noticing changes in his behavior, and didn't know why."

The family has not filed a lawsuit over his death in May. But thousands of former players have sued the NFL over concussions, claiming the league withheld information about damaging effects of repeated head blows.

The NFL, without acknowledging wrongdoing, has agreed to pay into a fund that could top $1 billion to settle injury claims that include Alzheimer's disease, dementia and CTE-related suicides. A federal judge has approved the settlement, but the deal is on hold while critics of its terms appeal.

Scientists continue to debate the potential links among concussions, CTE and suicide. Concerns about repeated concussions have led to congressional hearings and new rules on when student and professional athletes can return to play.

Chris Nowinski of the Boston University-affiliated Concussion Legacy Foundation confirmed Robinson's CTE diagnosis.

He said that 88 of 92 NFL players whose brains have been tested there have shown evidence of CTE, along with 33 others who played college or high school football. The brains are studied posthumously when families seek testing.