![\"CTE-caused-by-brain-injury\"](\"\/federal\/files\/2018\/01\/CTE-caused-by-brain-injury.jpg\")
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Sections from two brains used in the current BU-led study. The left sample comes from a 17-year-old American male high school football player who died by suicide two days after a closed-head impact injury. The brown stain indicates a widespread immune response, pointing to an abnormal increase in the number of astrocytes, a type of helper cell in the brain, due to the destruction of nearby neurons. The sample on the right, from the control group, shows the brain of a 22-year-old American male former high school football player who also died by suicide, with no history of recent head injury. Images courtesy of BU School of Medicine.<\/em><\/p>\n A new\u00a0BU-led study<\/a>\u00a0published Thursday in the journal\u00a0Brain\u00a0<\/em>suggests that chronic traumatic encephalopathy (CTE) is caused by head injuries, not by concussions. The research explains why 20 percent of athletes who exhibited the early stages of the progressive brain illness postmortem never had a diagnosed concussion.<\/p>\n \u201cIt\u2019s the hits to the head, not concussion, that trigger CTE,\u201d says\u00a0study\u00a0coauthor\u00a0Lee Goldstein<\/a>, a School of Medicine associate professor of psychiatry, who also has an appointment at the College of Engineering.<\/p>\n The study suggests that head injuries can cause blood vessels to leak proteins into adjacent brain tissues, inflaming them. CTE is a brain disease characterized by accumulation of tau protein around the brain\u2019s blood vessels. It is found in athletes, soldiers, and others who have suffered repeated concussions and other brain trauma and is associated with dementia, mood changes, and aggression. Concussions are injuries that impair a person\u2019s functions, such as memory or balance.<\/p>\n The study\u2019s finding is important because efforts to protect athletes focus on preventing concussions rather than repeated hits to the head, says\u00a0Christopher Nowinski,<\/a>\u00a0co-founder and CEO of the Concussion Legacy Foundation.<\/p>\n \u201cIn order to reduce CTE risk\u201d in athletes and military veterans, \u201cthere must be a reduction in the number of head impacts,\u201d says\u00a0Ann McKee<\/a>, director of the CTE Center and another study coauthor. \u201cThe continued focus on concussion and symptomatic recovery does not address the fundamental danger these activities pose to human health.\u201d<\/p>\n McKee<\/a>\u00a0and her team first examined the brains of four dead teenage athletes who\u2019d suffered head injuries one, 2, 10, and 128 days before they died. They found a range of post-trauma pathologies, including one case of early CTE (the disease has four stages) and two brains with abnormal tau accumulations. When researchers compared the brains to those of four teenage athletes who had not suffered recent head trauma, they found that those brains did not have the same pathologies.<\/p>\n The researchers speculated that early CTE could result from damaged brain blood vessels that leak blood proteins into nearby tissue, causing inflammation of the brain. They tested the hypothesis by exposing lab mice to two different triggers linked to CTE: repeated head impacts and blast exposures.<\/p>\n They then scanned the mice brains and found leaky blood vessels, as well as persistent changes in electrical functions, possibly explaining cognitive impairment in some people after similar injuries.<\/p>\n \u201cThe same brain pathology that we observed in teenagers after head injury was also present in head-injured mice,\u201d says Goldstein. \u201cWe were surprised that the brain pathology was unrelated to signs of concussion.\u201d<\/p>\n The findings, he adds, \u201cprovide strong causal evidence\u201d linking head impacts to both traumatic brain injury and early CTE, \u201cindependent of concussion.\u201d<\/p>\n The researchers focused especially on capillaries, the smallest \u201cand most important blood vessels\u201d in the brain, Goldstein says, through which oxygen, nutrients, and waste removal occur. \u201cHead impact results in focal disruption\u201d of capillaries, resulting in proteins leaking into the brain, he says.<\/p>\n The researchers also used computer simulations from\u00a0Lawrence Livermore National Laboratory<\/a>\u00a0and mechanical models from BU, both of which showed that triggers for concussion and CTE may be distinct.<\/p>\n The study, by a multinational team of universities and government agencies from the United Sates, Israel, Canada, and the United Kingdom, was funded by the\u00a0National Institutes of Health<\/a>, the\u00a0Department of Veterans Affairs<\/a>, the\u00a0US Department of Defense<\/a>, the\u00a0US Department of Energy<\/a>, and the\u00a0National Football League<\/a>,\u00a0among others.<\/em><\/p>\n\n
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