LOS ANGELES, Sept. 17 (Xinhua) -- Repeated head impacts from contact sports can trigger early and lasting changes in the brains of young to middle-aged athletes, potentially years before the onset of chronic traumatic encephalopathy (CTE), according to new research supported by the U.S. National Institutes of Health (NIH). The study suggests these brain changes may occur years before the hallmark features of CTE, which can currently only be confirmed through postmortem brain tissue examination, the NIH said in a release on Wednesday. Scientists at the Boston University CTE Center, the U.S. Department of Veterans Affairs Boston Healthcare System and collaborating institutions analyzed postmortem brain tissue from athletes under age 51, most of whom had played American football. "This study underscores that many changes in the brain can occur after repetitive head impacts," said Walter Koroshetz, director of NIH's National Institute of Neurological Disorders and Stroke. "These early brain changes might help diagnose and treat CTE earlier than is currently possible now."