Tammy and Ted Plevretes don't need more research to link football concussions to devastating brain damage.

They need only look across the kitchen table, where their 23-year-old son Preston sits mostly silent in a wheelchair, a home-health aide at his side.

Four years ago, Preston took the field for La Salle University a month after an earlier concussion. He collided head-on with an opposing player on a punt return at Duquesne University on Nov. 5, 2005. He was briefly knocked unconscious, awoke and was combative for a few minutes, then lapsed into a coma.

He survived lifesaving surgery to remove a massive blood clot, and has since endured three more brain operations, a trip overseas for a stem-cell transplant and years of grueling therapy. Yet his progress has been limited, and he struggles to walk and talk.

This fall _ amid rising awareness in the NFL about the long-term effects on the brain of repeated concussions _ the Plevretes family settled a lawsuit against La Salle for $7.5 million. The suit charged that the Philadelphia school failed to treat Preston's first concussion properly, causing the later catastrophic injuries from what some doctors call "second-impact syndrome." La Salle argued the injuries stemmed solely from the hit at Duquesne.

"We still love football. We don't want anyone to stop playing it," said Tammy Plevretes, 49, of Marlboro, N.J., whose 60-year-old husband once played for the rough-and-tumble, semi-pro Brooklyn Mariners.

"(But) I think kids need to see what can happen," she said. "This isn't a broken leg. It's a broken life."

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Preston was fortunate to be injured a few blocks from Mercy Hospital in Pittsburgh, where a pair of neurosurgeons on duty whisked him into an operating room. They removed a massive hematoma, staunched the bleeding and relieved the near-fatal pressure inside his skull.

Dr. Robert Cantu, a Boston-area neurosurgeon, served as the family's medical expert for the lawsuit. Cantu testified at this year's Congressional hearings on NFL concussions, telling lawmakers there is "growing and convincing evidence" that repetitive concussions can cause degenerative brain disease.

Preston's erratic on-field behavior, combined with the excessive bleeding, point to second-impact syndrome, he said.

"He enters the game symptomatic (for concussion). That sets him up for another injury causing this malignant brain swelling," he said.

Once a person is vulnerable, additional brain trauma does not always have to be severe to cause devastating damage, Cantu said.