"[T]he white matter that forms the wiring deep in the brain had 'moderately severe' damage, and in some areas was missing entirely."

"The delicate tissue sheaths that insulate each biological circuit lay in 'disorganized clumps,' and throughout Mr. Card’s brain there was scarring and inflammation suggesting repeated trauma. This was not C.T.E., the report said. It was a characteristic pattern of damage that has been found before in military veterans who were repeatedly exposed to weapons blasts during their service."

From "Profound Damage Found in Maine Gunman’s Brain, Possibly From Blasts/A laboratory found a pattern of cell damage that has been seen in veterans exposed to weapons blasts, and said it probably played a role in symptoms the gunman displayed before the shooting" (NYT).

Mr. Card = Robert Card, who had been a grenade instructor in the Army Reserve and, after 8 years of exposure to blasts, "began hearing voices" and experiencing "paranoid delusions." He killed 18.