Maine mass shooter 'likely' suffered from traumatic brain injury: Report

Robert Card, the man who killed 18 in the Lewiston, Maine mass shooting last year, “likely” suffered from traumatic brain injury, according to a report by doctors who studied his brain, and released by Card’s family.

The Maine Chief Medical Examiner’s office had requested the post-mortem study of Card’s brain by the Boston University CTE Center, and the results were shared by Card’s family on Wednesday.

Card had been a U.S. Army Reservist and a longtime instructor at an Army hand grenade training range, and it is believed that he was exposed to thousands of low-level blasts, according to doctors at Boston University’s Concussion Legacy Foundation.

“Robert Card had evidence of traumatic brain injury. In the white matter, the nerve fibers that allow for communication between different areas of the brain, there was significant degeneration, axonal and myelin loss, inflammation, and small blood vessel injury. There was no evidence of chronic traumatic encephalopathy (CTE),” Dr. Ann McKee, director of the BU CTE Center said in the report.

CTE is a progressive brain disease caused by repeated traumatic brain injuries. It is associated with significant behavior changes and dementia.

Traumatic brain injury is caused by a blow to the head. Mild injury may only affect the brain temporarily, while more serious injury can result in bruising, bleeding or more serious damage, and "can cause temporary or short-term problems with normal brain function, including problems with how the person thinks, understands, moves, communicates, and acts," according to the National Institutes of Health.

“These findings align with our previous studies on the effects of blast injury in humans and experimental models. While I cannot say with certainty that these pathological findings underlie Mr. Card’s behavioral changes in the last 10 months of life, based on our previous work, brain injury likely played a role in his symptoms.”

On Thursday, the Army released a statement reacting to the report's findings.

"The lab findings included in SFC Card’s autopsy report indicating brain injury are concerning and underscore the Army’s need to do all it can to protect Soldiers against blast-induced injury," the statement read.

"Currently, OSD and the Army are updating guidance on how to mitigate risks from blast overpressure," the statement continued.

On October 25, Card killed 18 and injured 13 after opening fire at a local bar and bowling alley before dying by suicide.

Card’s family is allowing further studies to be done on his brain in an effort to “help prevent future tragedies” from occurring.

Card’s family said in the Wednesday release they are deeply sorry for his actions and are “hurting” for survivors and members of the Lewiston community.

“While we cannot go back, we are releasing the findings of Robert’s brain study with the goal of supporting ongoing efforts to learn from this tragedy to ensure it never happens again,” his family said in a statement. “We know it does not fully explain Robert’s actions, nor is it an excuse for the horrific suffering he caused, but we thank Dr. McKee for helping us understand his brain damage and how it may have impacted his mental health and behavior. By releasing these findings, we hope to raise awareness of traumatic brain injury among military service members, and we encourage more research and support for military service members with traumatic brain injuries. Our hearts remain with the victims, survivors, and their families.”

-- ABC News' Luis Martinez contributed to this report.