Nicole Herling was praying for brain disease.
That’s rarely happy news. But for her, it offered a potential answer to a haunting question: why, in less than a year, had her brother transformed from a quiet Maine father to a ranting gunman who killed 18 people? After grappling with feelings of loss, anger and shame, Robert Card’s family hoped for the only consolation left.
“I was asking God … ‘Why?’” Herling said. “Please have something come out of this. Because I don’t know if I can live with thinking that my brother was capable of doing what he had done.”
For months, she waited for researchers at Boston University to present their analysis of the parts of her brother’s brain that had not been lost to his suicide. She wondered if they would find evidence of Chronic Traumatic Encephalopathy (CTE), a degenerative brain disease that has been linked to a host of cognitive, mood and behavior symptoms. Her brother had grown increasingly paranoid throughout 2023 and had been diagnosed with psychosis three months before the shooting.
They didn’t find CTE. But Dr. Ann McKee, who runs the university’s CTE and Alzheimer’s Disease Research Centers, observed “profound changes” in the structure of the gunman’s brain: severe degeneration of the white matter, inflammation, and a substantial thickening of small blood vessels.
Based on her research and what the family told McKee’s team about his exposure to grenade blasts and lack of sports injuries, she determined that damage was “likely” caused by his work as a weapons range instructor for the Army Reserve and probably contributed to his behavior changes.
Suddenly, Herling and her husband had a new calling: to advocate for the military to better protect service members’ brains from the explosions they are regularly exposed to in the field and on the training range — exposures that have increasingly been linked to traumatic brain injury, or TBI.
“I want to make sure that there's accountability. I want to see that happen,” Herling said. She cannot help but wonder if her brother’s brain damage — and the massacre in Lewiston — could have been prevented if the Army had implemented better brain safety policies.
The military doesn’t see it that way.
After the Army conducted its own investigation, the then-head of the Reserves told reporters gathered at the Pentagon last July that there was no evidence that the shooter’s brain injuries had occurred on grenade ranges and that he had not been exposed to enough blasts for this theory to make sense.
Instead, she suggested, he was probably hurt while off-duty, perhaps when he had a serious fall and broke his neck some 15 years before the mass shooting.
Lawmakers like Maine Sens. Angus King and Susan Collins, have questioned the Army’s conclusion and have introduced new legislation to push the military to move faster to improve brain safety policies.
“It’s indicative, I think, of not taking the problem as seriously as it should be,” King said.
Scientists have not been able to determine what level of blast exposure can be considered safe. And because the military does not currently have a comprehensive blast monitoring program, no one really knows how many times Card was exposed.
Though there’s clear evidence that repeated brain injury is linked to an increased risk of adverse brain health outcomes, doctors can not definitively link brain injuries with specific behavioral changes in individual cases.
“Everybody wants A to cause B, right? It’s just too simple,” McKee said in an interview at her office in December, conducted as part of a collaboration with the Press Herald, Maine Public, and FRONTLINE. “When you say, ‘Did that brain injury cause him to kill 18 people?’ Well, I can’t say that. You know, you can’t. It probably contributed to the story. But how much it contributed, that I don’t know.”
Kathy Lee, the director of the Department of Defense’s Warfighter Brain Health Initiative, says the military recognizes the seriousness of the problem and is working as quickly as possible to better understand how service members sustain these injuries, how the military can protect against them, and how doctors can detect and treat them.
“We want to take care of our people,” Lee said.
Experts and lawmakers praised recent safety policy changes as steps in the right direction. But they also warned that gray areas in brain science have long allowed institutions like the military to minimize their role in the problem — and to avoid moving as quickly as possible to find solutions. They say that failing to break out of that pattern could leave many Americans vulnerable.
'The mind is what the brain does'
Dr. Richard Carmona had his first experience with brain injury the same way many Americans do: playing high school football.
He says he was probably 15 years old when he lined up at running back, cut through the hole in the defensive line — and crashed into an oncoming linebacker.
Carmona didn’t understand anything was wrong until an hour after practice ended, when he realized he was still in his uniform; he had been too disoriented to change.
A day later, he was back in school and back in pads. In the 1960s, that’s just how things were.
“Basically, there were no protocols at that time,” said Carmona, a former U.S. Surgeon General who now serves on the veteran advisory board at the nonprofit Concussion Legacy Foundation. “If you could eat and walk, you were OK to play.”
That’s no longer true. Over the past several decades, doctors and researchers have developed a new understanding of how both individual, heavy blows and repeated, smaller physical impacts can affect long-term brain health.
The brain is made up of a complicated web of neurons, other microscopic cells and blood vessels. Besides controlling our bodies, this network governs everything that makes us who we are — our personalities, our desires, our ability to regulate emotions and behave in socially acceptable ways.
“Everything psychological is also biological. The mind is what the brain does,” said Michael Burman, a psychology professor at the University of New England.
The organ is as fragile as it is important.
Physical hits and other impacts can rattle the brain, stretching or tearing connections within and between different parts. Damaged blood vessels might fail to deliver the glucose and oxygen that sustain brain cells. Injured cells release chemicals that can trigger a surge of electrical activity within the brain, resulting in symptoms like loss of consciousness, amnesia and confusion.
In some cases, a single impact can have lasting consequences depending on the location of the injury. If a person’s prefrontal cortex behind the eyes and forehead is damaged, for example, they may no longer be able to effectively regulate their emotions.
But multiple, smaller hits — even when none of them cause obvious symptoms — can also be dangerous, according to Dr. Alexandra Stillman, the director of Concussion, Traumatic Brain Injury & Neurorehabilitation at Boston’s Beth Israel Deaconess Medical Center.
In a healthy brain, “helper cells” called astrocytes and glial cells function like tiny airbags, absorbing some of the impact and directing it away from neurons, Stillman said. If a person experiences a second impact before the body has had time to repair its supply of astrocytes and glial cells, the brain is left vulnerable.
And as these smaller hits accumulate, proteins released by damaged cells can spread to healthier parts of the brain, which can eventually contribute to the development and progression of CTE, the neurodegenerative condition.
High-profile cases, like the 2015 murder conviction and subsequent suicide of former New England Patriots tight end Aaron Hernandez, have brought public attention to CTE, which has been linked to cognitive, mood and behavior symptoms.
Research has suggested that the condition is alarmingly common among certain groups — scientists at Boston University announced in 2023 they had found CTE in the brains of 92% of 376 deceased former NFL players the team studied.
Like some other types of brain injury, CTE can currently only be diagnosed after death, making it difficult to identify and treat.
The growing understanding of brain injuries has prompted reforms at every level of athletics. When football players suffer a suspected concussion — whether they’re in high school or the pros — protocols passed in the last two decades require they stay off the field until they heal. When that doesn’t happen, teams are increasingly scrutinized by a public that recognizes the long-term consequences of head injury.
“For people that are at a higher risk for repeated trauma, typically we always err on the side of extreme caution,” Stillman said.
But even as groups like the Concussion Legacy Foundation began spotlighting the dangers of repeated blows to the head in the mid-2000s, the military was just beginning to understand that some American service members were losing their wellbeing and even their lives to a different manner of brain injury — one that didn’t involve a physical impact at all.
'No time to wait'
No one was sure exactly why hundreds of thousands of service members were coming home from the wars in Afghanistan and Iraq with brain injuries — a rate so staggering that the Department of Defense has regularly referred to TBI as a “signature injury” of those wars.
The main focus at the time was on enemy improvised explosive devices, or IEDs, according to David Borkholder, an engineer who began working with the DOD’s Defense Advanced Research Projects Agency in 2010 to study the problem. But the data suggested the issue was closer to home.
Borkholder, professor emeritus at the Rochester Institute of Technology, developed a gauge that service members could wear to measure their exposure to “blast overpressure” — the rapid changes in air pressure that occur near explosions and other blasts.
Two separate deployments of soldiers equipped with gauges in Afghanistan experienced a surprising level of blast overpressure— mostly from their own weapons.
“It wasn’t incoming fire. It was outgoing fire,” Borkholder said. “And the majority of those were happening in training.”
There are different theories on how blasts injure the brain. The conventional school of thought is that the pressure waves released by high-powered devices like anti-tank weapons, mortars and other explosives travel through brain tissue, leaving behind small tears.
Dr. Lee Goldstein, a BU researcher who also analyzed Card’s brain, does not believe overpressure is the culprit.
His studies, including two widely-cited papers, show that the initial pressure wave rapidly passes through the brain. But the sharp gusts of wind that follow can jerk the head, causing the same type of shearing in the brain that is found in football players and others who experience physical blows.
“The motion is contributory,” Goldstein said. “It explains why these very disparate insults like sports-related injuries, fast boats and blasts all result in the same injury: well, it’s because the mechanism of injury is the same.”
There are many questions that scientists are still investigating such as the minimum level of blasts that can be dangerous to humans, or what makes some people susceptible to injury while others are more resilient.
The defense department has understood for years that it needs to collect more data, Borkholder said. But there remain questions about the best way to do that.
The early research was concerning enough to attract attention from lawmakers. Motivated in part by a report by the Center for a New American Security that highlighted the dangers of blasts, Congress directed the Secretary of Defense to conduct “a longitudinal (long-term) medical study on blast pressure exposure of members of the Armed Forces during combat and training.”
The 2018 National Defense Authorization Act tasked the DOD with collecting and analyzing data on blast pressure exposure for any service member deemed likely to be around blasts in training or combat.
But that’s not exactly what happened, said Paul Scharre, one of the authors of the CNAS report.
Instead, he said, the DOD spent the next several years funding many small-scale studies and a pilot program, several of which looked at the question of whether it was feasible to capture and track blast exposures on an individual level but did not actually attempt that task on a large scale. “Which is not what the legislation tasked them to do and doesn’t really help,” Scharre said.
Lee, the DOD’s brain health policy director, said in an email that the multiple study approach allowed the military to explore a broader range of questions than a single longitudinal study would have.
Though Scharre and Borkholder both said they wish the military was moving faster to gather data on blast safety, they also praised recent military policy changes as good first steps.
Deputy Defense Secretary Kathleen Hicks signed a policy memorandum last August outlining several reforms, including new training standards that aim to minimize the number of people in the direct vicinity of blasts and the number of excess training rounds fired.
As of the end of 2024, all new active troops and reservists now undergo cognitive assessments — baseline tests that can be used to help diagnose service members with brain injuries in the future. The military will “accelerate” testing of current active-duty service members who are deemed “high-risk” by the end of the current fiscal year, with almost all other service members following “as soon as possible,” according to Hicks’ policy memo.
“We aren’t waiting,” said Lee. “We have no time to wait.”
Opposing findings
As BU researchers studied Card’s brain last winter, Herling and other family members told staff everything they could recall about his medical history — including that he had been exposed to potentially thousands of blasts while serving as a training instructor in the Army Reserve.
Herling doesn’t believe that there is any record of the number of blasts Card was exposed to during his two decades in the Reserves. Army records obtained through a Freedom of Information Act request indicate that from the time he transferred from New Hampshire in 2014, he usually spent the unit’s annual two-week mission training West Point cadets on the hand grenade range. Those records also show that this typically involved training more than 1,000 young soldiers per summer.
McKee said she used that history (and his lack of sports-related injuries) to connect the damage she saw under the microscope to her prior research on service members and blast exposure. She determined that Card’s injuries were “most likely secondary to that exposure” and that the damage likely contributed to the behavior changes he displayed in the last months of his life — though she could not say that with certainty.
Card’s family saw McKee’s findings as a way forward.
“It was just a validation that she does believe that Robbie had been exposed,” Herling said.
In May, she and her husband used part of their testimony in front of the Maine commission investigating the shooting to call on the defense department to do a better job protecting service members from blasts.
“Though we cannot undo Robbie’s tragedy, we can leverage this experience to spotlight the danger of brain injury for soldiers and their families,” Herling told the commission. She said the DOD, “must be held accountable for change.”
But Herling soon found herself again at odds with the military.
In July, four months after the release of the BU analysis, the Army shared its own report on Card’s death. The 115-page document notes that McKee’s team “could not conclude” whether exposure to blasts caused Card’s brain damage.
When pressed by reporters at a press conference at the Pentagon, then-Army Reserve Chief Lt. Gen. Jody Daniels said Card was likely injured while off duty and pointed to a 2008 fall from a roof that sent Card to the hospital with a broken neck.
Herling, who had told the Army about Card’s fall in cooperation with the investigation, felt betrayed.
Daniels said the reservist only had “relatively minor” blast exposure, suggesting that BU’s explanation did not make sense. She has since retired.
McKee, whose team has received funding from the DOD to study athletes and service members’ brains, said she has not had direct contact with the military about Card’s case and did not hear Daniels’ comments directly. But, she said the pattern of damage she observed in his brain, based on her years of experience, would take multiple blasts or impacts to cause — not just one fall or hit.
“We've never seen the type of brain injury… after a single event such as a fall,” she said. “Could that single injury have made the other injury worse? ... It's possible that it added to it. But as a single event, it doesn't explain the changes we found under the microscope."
'We need to protect these people now'
For several years, the DOD has understood that high-powered weapons like the Carl Gustaf recoilless rifle can produce dangerous pressure waves. It has already begun taking steps to limit service members’ exposure on the training range, including mapping where onlookers should stand to avoid overpressure exceeding 4 psi, which is currently the military’s best-guess safety threshold.
Still, after years of research, scientists don’t really know what that threshold should be. Service members exposed to blast overpressure levels lower than 4 psi are not subject to several of the new safety guidelines the DOD introduced in August. Hand grenades are not on the DOD’s list of weapons known to produce potentially dangerous overpressure levels, meaning it’s not clear if the new policies would have changed how Card did his work on the range.
“Successfully executed” grenades result in low blast overpressure, according to Lee, the head of the defense department’s brain health initiative, though she acknowledged the military has “limited exposure data” and is currently conducting further studies.
She said the military is moving swiftly to get firmer answers about what pressure levels are safe for both individual and chronic exposure to blasts and has a plan to identify that threshold by 2027. She said that the DOD instituted the interim 4 psi threshold — which is based on lung, ear and some brain research — because it recognizes that it must take steps to improve safety even if no definitive answers are yet available.
“We didn’t wait for the research to be finished and then say, ‘OK, we’re ready to now deploy this solution,’” she said. “We got 80% solution, and so we pushed that out early.”
Other project goals include improving brain injury detection tools, as well as designing and implementing a blast monitoring program to track exposure among at-risk service members.
The DOD has recently completed an analysis of several options, including placing blast gauges on service members, estimating their exposure levels based on what’s typical for others in their specialty, and circulating detailed questionnaires to service members to gather information about their experience with blasts.
The analysis, which has not yet been made public, will look at how effective, feasible and costly it would be for the department to implement each of these programs on a wide scale, Lee said.
She said that a longitudinal study centering on blast gauges will have “considerably higher costs” than a much smaller two-year study that followed fewer than 250 participants and cost more than $42 million.
“There’s other mechanisms and other ways you can try to document blast exposure,” Lee said. “You don’t just have to put blast gauges on somebody.”
Lee said the military is investigating both blast overpressure, and the blast wind theory favored by Goldstein, the Boston University researcher.
But recent DOD policy on the issue has mostly focused on blast overpressure — including the changes in the August memo titled “Department of Defense Requirements for Managing Brain Health Risks from Blast Overpressure.”
While the difference is subtle, Goldstein says focusing on the pressure wave itself rather than the rapid jerk of the head could result in the military failing to anticipate other sources of head injury and to protect other service members who could be at risk, including the Navy speed boat crews recently featured in a New York Times investigation.
“If you misconstrue the problem,” Goldstein said, “you’re going to misconstrue the solution.”
Some experts say that the relationships between blasts, brain injuries and adverse health effects are so complex that the only way to understand them is to conduct a truly longitudinal study — to place blast gauges on everyone who could be exposed and track them for decades.
They say alternative methods of blast monitoring, like estimating exposure based on a service member’s specialty, are less effective because even very minor differences in position and environment can dramatically change how much of the pressure wave actually reaches a service member’s brain.
“We’re not going to get more information if we don’t collect the data,” said Scharre, the Executive Vice President and Director of Studies at the Center for a New American Security and coauthor of the 2018 report. “I think that there’s real opportunities that the DOD is missing to gather information that they’re not doing today.”
McKee said that a longitudinal study would help scientists better understand the relationship between blast exposure and brain injuries. But she, like Lee, emphasized the importance of acting quickly rather than waiting for perfect data.
“Those studies are extremely expensive — and just by their nature, they have to go on for decades,” McKee said. “But we need to protect the people now.”
'What the hell are you going to do?'
Walter Reed National Military Medical Center is conducting a forensic autopsy that could include a second opinion on the likelihood that Card’s brain damage could have been caused by hand grenade blasts. The Army has not yet filled Freedom of Information Act requests for a copy of the report.
Nicole Herling isn’t expecting much.
She and her husband are planning to start their own nonprofit to advocate for veteran brain health.
“And my question is what the hell are we going to do for the people that have traumatic brain injuries today? What are we going to do for their families who are experiencing it today?”
When the news came out that the New Year’s attacker in New Orleans had served in the Army, Herling said she immediately reached out to BU and asked them to investigate whether a blast-related brain injury could be involved.
“We have to be sure he has no brain injury,” she wrote in a text to a reporter.
While there is no specific cure for CTE or traumatic brain injury, patients’ symptoms can be managed with treatment — provided they seek care. Scientists are currently working on several advancements that could help doctors detect brain injuries in living patients, including imaging and blood tests.
Someday soon, doctors could begin clinical trials of advanced therapies designed to prevent the long term neurodegenerative effects associated with repeated head trauma.
“We have to be able to detect the injuries first and monitor them,” McKee, the BU researcher, said. “But we’re almost there.”
Lee said the DOD has a comprehensive plan to improve blast overpressure safety in the military. While scientists work on identifying accurate safety thresholds and developing diagnostic tools and advanced therapies, Lee said her team is dedicated to spreading the word about brain health so that service members and their commanding officers recognize symptoms and seek help early.
“We want to take care of our people.”
The Herlings are not alone in viewing the military with a skeptical eye.
Even as the Army distanced itself from the theory that Card’s brain damage could have been related to blasts, the story quickly drew the attention of Maine’s Congressional delegation.
“If there are ways that we can prevent brain injuries that may have contributed to a mass shooting, surely we should undertake those measures,” Collins, the Republican senator from Maine said. “We don’t know for certain that (blast exposure) was the complete cause of Robert Card’s serious mental illness, but the fact that at least the Boston University Center has found evidence of traumatic brain injury certainly raises the question of whether or not it played a role.”
Both she and King, an Independent who serves on the Senate’s Veterans’ Affairs and Armed Services committees, praised the military’s new cognitive baseline testing program as a good first step. Last spring, they both attached their names to the bipartisan Blast Overpressure Safety Act, which — among other steps — would require the DOD to improve their blast exposure and TBI data collection efforts and consider overpressure safety when purchasing new weapons systems.
Most of the bill’s provisions were included in the National Defense Authorization Act that passed Congress just before the end of last year.
King, who said he believes Card was injured in the line of duty and is “disappointed” that the Army has not acknowledged that, thinks the military should have already done more. Now, he’s especially focused on oversight — making sure that the DOD not only implements better safety policies, but actually follows them.
“I think it’s the instinct of any organization to defend itself,” he said. “We’re not going to let the military in any way avoid their responsibility to confront this.”
Maine Public Radio Deputy News Director Susan Sharon contributed to this reporting.
This story is part of a collaboration with FRONTLINE (PBS) and The Portland Press Herald that includes the documentary “Breakdown in Maine.” It is supported through FRONTLINE’s Local Journalism Initiative, which is funded by the John S. and James L. Knight Foundation.
