Joint Staff Surgeon Air Force Brigadier General Paul Friedrichs said it was "extraordinary" that no American soldiers were seriously injured in the January attack.
"A traumatic brain injury is life threatening, not just at the time, but for the rest of your life," the Democratic presidential candidate noted.
Boxer Patrick Day died Tuesday, four days after being knocked out in a boxing match in Chicago. He is one of at least four fighters to die from injuries suffered in the ring in 2019 alone.
Such damage has been seen only in people over 46. He was 27.
But the changes recover after rest.
Half of people who have suffered severe head injuries have trouble maintaining normal sleeping habits and often don't realize it's a problem.
Post-mortem analyses showed 96 percent had chronic traumatic encephalopathy.