Former San Francisco 49ers cornerback Phillip Adams, pictured in this 2010 photo, had CTE, a degenerative brain disease. Authorities say he shot and killed six people earlier this year before killing himself.

Former San Francisco 49ers cornerback Phillip Adams, pictured in this 2010 photo, had CTE, a degenerative brain disease. Authorities say he shot and killed six people earlier this year before killing himself. / AP

A former NFL player who shot and killed six people and then took his own life in April was suffering from a severe medical condition brought on by repeated head trauma, doctors announced Tuesday.

Boston University neuropathologists said Phillip Adams had CTE — or chronic traumatic encephalopathy — a degenerative brain disease found in many former football players.

"Phillip Adams had an extraordinary amount of CTE pathology in the frontal lobe, the area of the brain behind the forehead. Frontal lobe damage is associated with violent, impulsive or explosive behavior, a 'short fuse,' and lack of self-control," Dr. Ann McKee, director of the Boston University CTE Center, said in a statement.

"His CTE pathology might have contributed to his abnormal behaviors, in addition to other physical, psychiatric and psychosocial factors," she added.

The killings earlier this year shocked rural South Carolina and raised questions about the former cornerback's health. Authorities say on April 7, Adams went to the home of Dr. Robert Lesslie and shot him, his wife and two of their grandchildren, aged 9 and 5. He also shot and killed two air conditioning technicians who were working at the property.

Adams, 32, later killed himself during a standoff with police at his parents' home nearby.

Both families said the knowledge that Adams had CTE before he carried out the shootings brought them some solace.

"These eight months have been unimaginably difficult," the Lesslie family said in a statement, according to the Charlotte Observer. "Even in the midst of crushing heartbreak, we are finding some comfort in the CTE results and the explanation they provide for the irrational behaviors pertaining to this tragedy."

Adams' family said in a statement that it remained saddened by the killings and continued to pray for the victims. "We are pleased to have a better understanding of the mental turmoil that Phillip was dealing with during the last moments of his life," the family said. "We cannot say that we are surprised by these results, however it is shocking to hear how severe his condition was."

CTE can't be diagnosed during a person's life but only through an examination of their brain after they've died.

Doctors who studied Adams' brain said he had stage 2 CTE, which is the most common stage for football players diagnosed with the disease in their 30s. (Stage 4 CTE is the most severe, they said, and usually involves dementia.)

The disease is linked to mood changes and memory loss as well as aggression and impulsive behavior. It's unknown exactly what causes CTE and there is no cure.

A number of hockey players and especially U.S. football players, who experience blows to the head as part of the sport and sometimes develop concussions, have been shown to develop CTE.

Aaron Hernandez, the former New England Patriot who was convicted of murder in 2015 and later killed himself, had CTE that was similar in severity to Adams, doctors said.

Adams played tackle football for 21 years, beginning at age seven, and retired from the NFL in 2016.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Tags: chronic traumatic encephalopathy  CTE