BALTIMORE — Jonathan Martin believes he’s doing most things right.
A former offensive tackle with the Miami Dolphins and San Francisco 49ers, he retired at 26 before the sub-concussive head hits that are the hallmark of his position could do more damage. He shed 50 pounds, took up yoga and meditation and, after bouncing from job to job, enrolled in an M.B.A. program at the University of Pennsylvania.
But Martin, now 32, figures he had potentially dozens of concussions playing football and has had bouts of anxiety and depression, all symptoms associated with chronic traumatic encephalopathy, the degenerative brain disease that has plagued football players and was found posthumously in a former teammate who died at 26.