Evidence mounts over CTE injuries in NFL players Chronic traumatic encephalopathy is a degenerative neurological disease that can affect athletes in hard-contact sports, especially football and boxing. Repeated blows to the head may eventually cause symptoms, such as slurred speech, tremors and confusion. Depression and suicidal tendencies have also been noted. The NFL has resisted acknowledging links between those effects and concussion impacts. Joe DeLamielleure Mike Webster Buffalo Bills Pittsburgh Steelers retired 1985 died 2002 Tony Dorsett Leonard Marshall Dallas New York Giants Cowboys retired 1994 retired 1988 Junior Seau Dave Duerson San Diego Chicago Bears Chargers died 2011 died 2012 Retired and former NFL players thought to be affected by CTE Troubling symptoms and autopsy inspection of brain tissues in a growing number of retired or deceased NFL players have pushed CTE research into the public eye; the players above all showed signs of CTE; key to the condition is the behavior of a brain protein called Tau How concussions Direction Brain tissue comparison can impact of blow Coup the brain impact A coup injury occurs under the impact site of the head with an object • Cross section of a normal • Cross section of a brain brain, part of a database showing advanced CTE; tau maintained by researchers at protein deposits cause brain Boston University to shrink, become brittle • Football head impacts can • Immediate effects can include bring to bear forces nearly headache, dizziness, confusion, Dark deposits of tau proteins shown in samples 100 times the force of gravity nausea, difficulty hearing and seeing Brain relies on axons, microtubules to send signals Electrical impulses travel along axons to nerve Countrecoup impact synapses Direction of blow Contrecoup injury occurs • Sample from • Sample from • Sample from the Brain on side of head opposite a normal brain, brain of John brain of a deceased cell the impact of a 65-year-old Grimsley, an NFL boxer, age 73 at person, with veteran who died death; suffering Fragment magnified detail at age 45; tau from extreme form of tau deposits showing of CTE damage protein Deposits shown under greater magnification Key role of tau proteins • Tau proteins are needed to provide stability to tiny pathways within axons called microtubules • When tau breaks down, dementia or cognitive problems often develop How CTE destroys brain cells Axon What strong head impacts can do • A blow to the head can cause tearing in the protective Synapse myelin sheath around axons • In brain axons, • Repeated blows to • Tau proteins detach • Tau strands then microtubules carry the head cause from microtubules, bind to form tangled electrical signals modifications to tau causing them to fall masses, killing the from cell to synapse proteins apart brain cell Source: Boston University School of Medicine, Frontline, ChronicTraumatiCencephalopathy.com, NFL, New York Times, MCT Photo Service Graphic: Robert Dorrell © 2013 MCT.