U.N.C. Football Player Who Ended Up Homeless Had C.T.E.

For so long, Ryan Hoffman, a former college football player I wrote about last year, had the same explanation for his inability to get his life on track.

“Something is wrong with my brain,” said Hoffman, a former offensive lineman at the University of North Carolina who ended up a panhandler, homeless, penniless and dependent on drugs and alcohol.

Last week, his family learned that Hoffman, who was 41 when he died in November, was right.

Researchers at Boston University and the Concussion Legacy Foundation on Friday notified Hoffman’s family that an analysis of his brain showed evidence of C.T.E., or chronic traumatic encephalopathy, the degenerative brain disease believed to be caused by repeated hits to the head.

For the Hoffmans, it was the answer to the mystery of Ryan Hoffman’s continuing problems, which included jail time and joblessness — troubles that defined his life after a successful college career on a team ranked in the top 10.

“I wanted to know exactly what happened to my brother, and I just knew football did it,” his sister, Kira Soto, told me Monday in a phone call as she began to cry. “I’ve been looking into this for 15 years and defended him when people said it was just the drugs and judged him for something he couldn’t help, something that he struggled with. Well, we know now. We know.”

Dr. Ann McKee, the chief of neuropathology at the V.A. Boston Healthcare System and professor of neurology and pathology at Boston University School of Medicine, examined Hoffman’s brain and told me he had Stage 2 C.T.E., on her scale of 0 to 4. It was the same severity found in the brain of Tyler Sash, the former Giants safety who in September died of an accidental drug overdose, at 27, and in the brain of Junior Seau, who shot and killed himself in 2012.

Dr. McKee said that Stage 2 C.T.E. can be especially symptomatic, causing problems like depression, short-term memory loss, lack of impulse control, irritability and mood swings, and that some of those symptoms could be confused with mental illness. Last year, Hoffman told me that he had received diagnoses of various mental illnesses, including manic depression, but that medications never seemed to help.

Hoffman rode his bike into oncoming traffic, on a poorly lighted road in Haines City, Fla., in November. He was hit by a car, head on, and died on the way to the hospital. His mother, Irene Hoffman, said she was certain that he did not kill himself on purpose.

Brian J. McNulty, the Haines City assistant police chief, said on Monday that the investigation into Hoffman’s accident was still incomplete because Hoffman’s full autopsy — including the toxicology reports that go with it — was not yet available.