A Navy SEAL was convinced exposure to blasts damaged his brain, so he donated it to science to prove it

Before he ended his life, Ryan Larkin made his family promise to donate his brain to science.

The 29-year-old Navy SEAL was convinced years of exposure to blasts had badly damaged his brain, despite doctors telling him otherwise. He had downloaded dozens of research papers on traumatic brain injury out of frustration that no one was taking him seriously, his father said.

“He knew,” Frank Larkin said. “I’ve grown to understand that he was out to prove that he was hurt, and he wasn’t crazy.”

In 2017, a postmortem study found that Ryan Larkin, a combat medic and instructor who taught SEALs how to breach buildings with explosives, had a pattern of brain scarring unique to service members who’ve endured repeated explosions.

Seven years later, an Army reservist who carried out a high-profile mass shooting was also found to have brain damage, underscoring how much the research and technology needed to fully understand and treat traumatic brain injury is still lagging, experts and advocates said.

No scan can detect that level of brain trauma while a person is alive, according to Dr. Russell Gore, a medical director with the Shepherd Center’s SHARE Military Initiative, which treats veterans and service members with brain injuries. And while there is a tool that may be able to track some changes, it is mostly limited to research purposes.

“It’s a little bit of fringe medicine right now,” Gore said. “We’re really at an infant stage in terms of our clinical ability to assess traumatic brain injury.”

Earlier this month, the gunman behind Maine’s deadliest mass shooting put a national spotlight on the issue when doctors said they determined traumatic brain injury “likely played a role” in his behavioral changes.

Robert Card fatally shot 18 people in Lewiston, Maine, last October before dying by suicide at age 40, authorities said.

He enlisted in the Army Reserve in 2002 and had no combat deployments, officials said. But his family said he had been exposed to thousands of low-level blasts as a longtime instructor at an Army hand grenade training range.

Card’s postmortem brain study found “significant degeneration” and inflammation in the white matter — the nerve fibers that allow for communication between different areas of the brain, according to Dr. Ann McKee, the neurologist at Boston University’s Chronic Traumatic Encephalopathy (CTE) Center who led the study.

In a brief statement, McKee said there was no evidence of CTE, a condition found in football players who suffer repeated blows to the head.

The statement did not paint a full picture of Card’s health or trauma history, and the full analysis was not made public. McKee and the Boston University CTE Center declined to be interviewed, and Card’s family did not immediately comment.

But the findings, including the absence of CTE, mirror other postmortem scans of service members’ brains, according to Dr. James Stone, who was enlisted by NATO in 2021 to help develop guidelines for preventing serious brain injuries in service members. He said those guidelines are expected to be released this year.

Stone, an imaging expert who has studied low-level blasts in military personnel for nearly two decades, said Card’s injury “seemed pretty profound.”

“We need to, as soon as possible, answer the question of how much is too much when it comes to safe levels of exposures,” he said.

In a statement, the Army said Card’s findings were “concerning” and that it was currently updating guidance on how to mitigate risks from blast overpressure. A spokesperson said the Army’s goal is to require tracking of exposed personnel and documentation of training environments that exceed certain blast thresholds, beginning later this year.

The efforts come a year after the Pentagon’s Office of Inspector General issued a report saying the Defense Department did not consistently identify and assess service members for traumatic brain injuries and did not implement a consistent process to manage the injuries.

Frank Larkin, 68, who was also a Navy SEAL, said while traumatic brain injury was a topic of discussion about a decade before his son died, there has been “very little movement.”

“It’s unacceptable,” he said, “after 20-plus years of persistent conflict.”

‘The science isn’t there’

Symptoms of traumatic brain injury include persistent headaches or neck pain, fatigue, memory issues, trouble sleeping, concentration problems, chronic depression, anxiety and apathy, researchers say.

It can also lead to aggression and violence, experts say, but cases like Card’s that result in mass violence are rare. “These high-profile cases, thankfully, are few and far between,” Stone said. “But they are a point along the overall spectrum — the different ways that the imbalance can manifest.”

Ryan Larkin exhibited many symptoms of traumatic brain injury, his father said. “The changes we saw were uncharacteristic,” Frank Larkin said, adding that his son grew anxious and became short-fused.

Ryan Larkin sought help through the Navy and the VA, but doctors spoke little of traumatic brain injury and focused more on behavioral and psychiatric diagnoses “because that was what they knew,” his father said.

“We are handicapped by the fact that we can only really qualify this postmortem,” he said.

There is no imaging tool that can detect brain injuries like CTE, Gore said. While some researchers have detected structural white matter changes in the brain, Gore said the method is not yet legitimate or reliable in a clinical setting.

“Right now, the science isn’t there,” he said, “but there’s a lot more that could be done.”

Logging exposure to low-level blasts is a good start, advocates say.

Jon Retzer, who served in the infantry with the Army and then the Army National Guard in the 1990s, said exposure logs should be kept for service members in any role, even when they’re not deployed or engaged in combat.

Hand grenade instructors can cycle through hundreds of trainees in one day during annual or biannual qualifications that are mandatory for some units, according to Retzer, who now works for DAV, an advocacy group formerly known as Disabled American Veterans.

Retzer said the risk of being concussed is higher in certain training scenarios, particularly when trainees are taught to pull the safety pin and hold onto the grenade for a few moments instead of tossing it immediately.

When trainees hesitate for too long, instructors have to throw the grenade over the wall, which causes a close detonation, and then grab the trainee and lower both to the ground.

“That one has a significant feel to it,” he said. “You can see the dirt actually go right up over, and you can see the wave of dust that was produced.”

There were more than 492,000 traumatic brain injuries, mostly mild concussions, in the military between 2000 and 2023, the most recent year with available data, Defense Department statistics show.

But the total number of cases is likely higher. The current tally, Gore said, does not account for service members who have brain injury from low-level blasts over time.

And if a service member has had more than one traumatic brain injury, only one is counted, according to the Traumatic Brain Injury Center of Excellence, a congressionally mandated collaboration between the Defense Department and Veterans Affairs.

“This isn’t going away,” Frank Larkin said. “And my fear is that this is going to trail behind us for decades.”

If you or someone you know is in crisis, call 988 to reach the Suicide and Crisis Lifeline. You can also call the network, previously known as the National Suicide Prevention Lifeline, at 800-273-8255, text HOME to 741741 or visit SpeakingOfSuicide.com/resources for additional resources.

This article was originally published on NBCNews.com