Sen. Jerry Moran, R-Kan., chairman of the Senate Veterans’ Affairs Committee, left, speaks with a staffer on Thursday, July 24, 2025, during a Senate hearing. (Eric Kayne/Stars and Stripes)
WASHINGTON — Brain injuries and mental health problems diagnosed in veterans exposed to repeated low-level blasts from firing their own weapons would be closely tracked and studied under legislation sponsored by Sen. Jerry Moran, R-Kan., who is chairman of the Senate Veterans’ Affairs Committee.
The Precision Brain Health Research Act aims to expand knowledge on potential links between frequent low-level blasts and the risks of mental health problems, cognitive delays and suicide among veterans, according to the legislation. It would authorize studies on treatments within the Department of Veterans Affairs that are yielding positive outcomes.
Low-level blasts are generated from firing heavy weapons systems and detonating explosives in combat and training, according to the Defense Department. But the military’s understanding about the full impact on service members and veterans is still “emerging” as research is conducted, the Defense Department said.
The bill’s supporters contend the legislation is necessary because most studies have focused on high-impact blasts, such as explosions from roadside bombs. But there is far less information about potential health risks of low-level blasts from repeatedly firing weapons or working in areas where there is indirect weapons fire, according to lawmakers.
“We have a duty to expand our understanding of the impact these blasts have on mental health, and to protect the long-term health and well-being of our military community,” said Sen. Angus King, I-Maine, a member of the Senate Veterans’ Affairs Committee and co-sponsor of the bill.
The legislation would direct the Defense Department and the VA to share data on low-level blast exposures to further research and improve treatment.
But it is common for service members who have had low-level blast exposures not to have an immediate diagnosable injury, according to the Defense Department. Health problems may develop over time.
That was the case for Ryan Larkin, who served as a Navy SEAL from 2006 to 2016.
“My son was not the same guy when he came home from the military,” said Frank Larkin of Maryland, whose 29-year-old son died by suicide in 2017. “The bottom line is that the military has not put a priority on looking into this. I am driven to get some results on behalf of the men and women who’ve served this nation and now are being left behind.”
Frank Larkin of Maryland, a former Navy SEAL, is pushing for legislation to expand research into the effects of low-level blast exposures on the mental health of service members and veterans. He is shown in his role as a firefighter-paramedic for the city of Annapolis Fire Department. (Frank Larkin)
Ryan underwent conventional brain scans after he began to experience mental health problems, Frank Larkin said. There were no signs of traumatic brain injury.
But a post-mortem study of Ryan Larkin’s brain tissue showed extensive microscopic scarring. Doctors connected his undiagnosed brain injury to “overpressure exposure to explosives and weapons systems.”
Frank Larkin had donated his son’s brain for medical research at Uniformed Services University, which conducts studies on brain injuries on military personnel. The university has a tissue repository where more than 500 brains have been studied for blast exposures.
Blast overpressure refers to the rapid increase in atmospheric pressure caused by the shock wave from an explosion or weapon discharge, according to the Defense Department.
Ryan Larkin had served as a special warfare operator first class with deployments to Iraq, Lebanon and Afghanistan. He then worked for two years as an “urban combat trainer” at several military training sites in California prior to his discharge.
Ryan Larkin served as a Navy SEAL from 2006 to 2016. “My son was not the same guy when he came home from the military,” said Frank Larkin, whose 29-year-old son died by suicide in 2017. A post-mortem study of Ryan Larkin’s brain tissue conducted at Uniformed Services University showed microscopic scarring that doctors said was from low-level blast exposures. (Frank Larkin)
He had used multiple weapons systems that included shoulder-fired rockets and concussion grenades, Frank Larkin said. Concussion grenades are non-lethal and produce a loud bang.
But Ryan increasingly became withdrawn and “devoid of emotion,” Frank Larkin said. He struggled to carry out his duties and was reassigned to a desk job in logistics in 2015. He left the military a year later.
“Ryan said there is something wrong with my head, but no one is listening to me,” Frank Larkin said. “His doctors tried over 40 different prescriptions. But they could never settle on what was going on with him.”
Low-level blasts do not necessarily cause a concussion or TBI that can be diagnosed by MRIs and other brain scans, according to the Defense Department. But the damage can lead to lasting cognitive problems, such as losses in focus, memory and critical thinking skills.
Frank Larkin said he saw those symptoms in his son and did not connect them to a possible brain injury from low-level blasts.
“It was not at the front of anyone’s assessments” in the military or the VA, he said.
“When weapons are fired, invisible blast waves move through the brains of anyone nearby, which can cause inflammation and damage brain cells and blood vessels. Repeated exposure to blast waves — even smaller ones — can cause brain changes, including structural differences and degeneration,” according to the American Brain Foundation.
The Defense Department has identified military occupations and weapons that bring a higher risk of brain injury from low-level blasts. They include jobs in armor, artillery, weapons training, explosive ordinance disposal and gunnery. The use of shoulder-mounted weapons, .50 caliber weapons and breaching charges also were identified.
But a 2024 study by Rand, a nonprofit research organization, identified a knowledge gap about the effects from exposure to low-level blasts in the military. The study recommended the use of surveillance tools, such as blast gauges, to monitor and collect data on service members’ exposure in training and combat.
“This legislation will help us start to better understand why and how blast exposures are impacting service members and veterans and make certain VA is able to quickly incorporate these findings into clinical care for our veterans to receive a diagnosis and a treatment plan,” Moran said.
