The Lewiston gunman’s experience conducting grenade training exercises for the U.S. Army – which likely led to a traumatic brain injury and his behavioral changes leading up to the mass shooting last fall – could lead to changes in training protocols, the Army said on Thursday.

Maine Shooting

Robert Card

Robert Card, an Army reservist, was “exposed to thousands of low-level blasts” during years of grenade training in New York state, according to personnel records and a forensic analysis of Card’s brain tissue conducted by Boston University that was released on Wednesday. Brain injury likely played a role in his declining mental health before the mass shooting, it said.

Card was hearing voices and believed people were spreading lies about him before he shot and killed 18 people in Lewiston on Oct. 25. His body was found about 48 hours later in a Lisbon storage trailer. The medical examiner said that he died from a self-inflicted gunshot wound.

“The lab findings included in (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 Army’s Office of the Chief of Public Affairs said in a statement Thursday. “Currently, the Office of Secretary of Defense and the Army are updating guidance on how to mitigate risks from blast overpressure.”

“In the near future, the Army will begin an Army-wide blast overpressure safety campaign to increase understanding of potential risks, direct risk mitigation actions, require documentation of training environments that exceed 4 PSI (pounds per square inch), and require tracking of exposed personnel.” And, it said, the Army will “convene key stakeholders to determine what additional actions, investments and research may be needed to best protect soldiers from blast-related injury in the future.”

The extent to which Card’s brain injury played a role in the tragedy is unknown, but research shows that brain injuries can cause people to experience behavioral changes and lose cognitive functioning.


Am expert in neuroscience told the Press Herald on Thursday that traumatic brain injuries can cause the brain to malfunction to the point that people who previously were leading normal lives can lose their ability to regulate their emotions, leading to erratic behavior.

Michael Burman, a professor of neuroscience at the University of New England, which has campuses in Biddeford and Portland, was not involved in the brain tissue analysis conducted by Boston University.

But speaking generally about brain injuries, Burman said that because injuries to the brain are hidden from view, they can be difficult to detect. It can be especially difficult to know what’s going on when there are numerous brain injuries over time.

“When there’s small amounts of damage, normally that’s not noticeable and there’s no impact on brain functioning,” Burman said. “But these can be cumulative and build over time. Eventually, you reach a tipping point.”

He said it’s like a hiker adding a pound to her backpack. The first few pounds may not cause much difference in how well the hiker can summit the mountain. But eventually, it’s too much.

But because brain injuries are out of sight, people don’t notice how devastating they can be to the person living with the injury.


And cumulative damage to the brain – such as frequent concussions or lower-level impacts – can eventually lead to numerous problems in brain function, Burman said. Card, 40, of Bowdoin, had displayed erratic and disturbing behavior in the months before the shooting, resulting in a two-week psychiatric hospitalization in New York in July 2023.

Burman said different parts of the brain specialize in certain functions, such as the hypothalmus and amygdala being the centers of primal emotions like fear and aggression. Meanwhile, the prefrontal cortex helps control those emotions.

“The prefrontal cortex is where we can process long-term goals, values and understand social norms,” Burman said. “It modulates our behavior.”

Maine Shooting

In this image taken from New York State Police body camera video, New York State police interview Army Reservist Robert Card, the man responsible for Maine’s deadliest mass shooting, at Camp Smith in Cortlandt, New York, on July 16, 2023. WMTW-TV 8/New York State Police via AP

When brain cells are damaged, they die and can never heal. But because the brain is built with a series of redundancies, when a small number of brain cells die, the brain can find other ways to cope and continue connecting and functioning normally.

But when injuries to the brain reach the point that the connections between the hypothalmus, amygdala and prefrontal cortex are compromised, it can lead to a downturn in the ability to function, Burman said.

“Those modulatory influences can become reduced. You can have emotions that result in risky, antisocial, terrible behavior and lose the ability to predict or feel the consequences of those actions,” Burman said. “So you can get those urges without having the brakes. It’s like the gas pedal is always on.”



Researchers at the Boston lab that tested Card’s brain did not respond to an interview request Thursday but told The New York Times this week that the findings raise new questions.

“We know very little about the risks of blast exposure,” Dr. Ann McKee, who leads the lab and signed the report, said in the Times. “I think these results should be a warning. We need to do more investigation.”

But McKee also said in a statement that “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.”

Burman said there have been enormous advances in the understanding of brain functioning during the past 20-30 years, leading to better treatments for those who are diagnosed with brain injuries. People diagnosed with brain injuries can train their brains – with help from therapists – to learn how to recognize and control irrational thoughts, he said.

Members of Maine’s congressional delegation had pressured the U.S. Army to investigate the events leading up to the shootings, which prompted the U.S. Army Inspector General to respond in December that the office would investigate and make recommendations for corrective actions. Whether recommendations on updating training protocols will be part of the report was unclear.



Matthew Felling, spokesman for Sen. Angus King, I-Maine, said that “we owe it to the Lewiston victims and their families to do everything in our power to see that this doesn’t happen again. This means following the data and the science to best assess the underlying causes of Robert Card’s actions, including possible preventable brain damage due to his assignment in the military. Senator King is tracking the neurological research and also awaiting the Army Inspector General’s report to inform the path forward to a safer future.”

Card’s family issued a public statement Wednesday for the first time since the shootings, expressing heartbreak for the victims and survivors of the mass shooting, and calling for more research into the risks of military service.

People hold candles and signal “I love you,” in American Sign Language at the end of a vigil on Nov 1, at Winthrop High School for victims of the Lewiston mass shooting. Joe Phelan/Kennebec Journal

“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,” the family said.

The statement also said family members would have no further comment and would not grant interviews. But a sister, Nicole Herling, told the Times that the findings of brain injury changed how her family saw the shooting and her brother.

“It allowed me to forgive him,” she said. “I know a lot of people are in a lot of pain. Maybe we can use what happened to help other people.”

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