Becoming punch drunk is not just a risk for professional boxers. There’s a risk of brain damage for the amateurs too, despite their use of head protection. That’s according to research being presented today at the American Academy of Neurology meeting in Boston.Doctors from the Sahlgrenska Hospital in Sweden performed spinal taps on boxers within 10 days of a fight. They found that their cerebrospinal fluid had four times the level of a protein called neurofilament light—which is associated with nerve damage—compared with levels found in non-athletes. Some boxers who took more than 15 hits to their head in one bout had brain damage equivalent to that of a minor stroke. Even wearing head gear, boxers’ brains smack against the skull with each blow, stretching blood vessels and damaging cells. Some good news though: the levels of markers for cell damage returned to normal after a three month hiatus from boxing. Dr. James Kelly, a brain injury expert at the University of Colorado said there might be the hope for some recovery for partially injured cells.