NEW : Researchers find start of brain damage in 18-year old athlete who died . NEW : Same type of brain damage found in sixth dead NFL player . Comment: Symptoms can include depression , sleep disorders , headaches .
NEW : Researchers find start of brain damage in 18-year old athlete who died . NEW : Same type of brain damage found in sixth dead NFL player . Damage from repeated concussions is called chronic traumatic encephalopathy . Symptoms can include depression , sleep disorders , headaches .