You’re likely already familiar with news articles linking brain concussions with injury to cognitive abilities. Now, using a form of magnetic resonance imaging (MRI), researchers at the Indiana University School of Medicine and the Geisel School of Medicine at Dartmouth College found significant differences in brain white matter of varsity football and hockey players compared with a group of noncontact-sport athletes following one season of competition. White matter is composed primarily of axons, the long fibers that transmit signals between neurons. According to Thomas W. McAllister MD, chair of the IU Department of Psychiatry: This study raises the question of whether we should look not only at concussions but also the number of times athletes receive blows to the head and the magnitude of those blows, whether or not they are diagnosed with a concussion.” Some athletes may be more susceptible to repeated head impacts that do not involve concussions, although much more research would be necessary to determine how to identify those athletes. More work would also be necessary to determine whether the effects of the nonconcussion head impacts are long-lasting or permanent, and whether they are cumulative.