We've known for a while that the head trauma from playing football can lead to the degenerative brain disease chronic traumatic encephalopathy (CTE). Now it turns out that some (many?) US Navy SEALS also have an unusual pattern of brain damage. It is traumatic brain injury due to repeatedly being exposed to blast waves, which occur from firing their own weapons or enemy action.
In 2016 a team of doctors put a name to the pattern of brain damage - interface astroglial scarring. It can result in such symptoms as gaps in memory, deteriorating memory, mood swings, headaches, impulsiveness, fatigue, and anxiety. The brain damage is not found in the brains of civilians, or in people exposed to a single massive explosion (e.g., from a roadside bomb). It is not PTSD (post traumatic stress disorder).
Unfortunately, at least 12 former Navy SEALS with this brain damage have committed suicide in the past decade. They were an average age of 43. None of them had been wounded by enemy fire, but all had spent years firing a wide variety of weapons and using explosives.
Many SEALS now alive say they are suffering from the same set of symptoms showing deteriorating brain function. A recent study confirmed this - the more blast exposure, the more symptoms and brain injury.
It is unknown how the military will deal with this issue, and whether and how training of SEALS will change.
Excerpts from an excellent article. Also read the online comments after the article. From NY Times: Pattern of Brain Damage Is Pervasive in Navy SEALs Who Died by Suicide
David Metcalf’s last act in life was an attempt to send a message — that years as a Navy SEAL had left his brain so damaged that he could barely recognize himself.
He died by suicide in his garage in North Carolina in 2019, after nearly 20 years in the Navy. But just before he died, he arranged a stack of books about brain injury by his side, and taped a note to the door that read, in part, “Gaps in memory, failing recognition, mood swings, headaches, impulsiveness, fatigue, anxiety, and paranoia were not who I was, but have become who I am. Each is worsening.”
Then he shot himself in the heart, preserving his brain to be analyzed by a state-of-the-art Defense Department laboratory in Maryland.
The lab found an unusual pattern of damage seen only in people exposed repeatedly to blast waves.
The vast majority of blast exposure for Navy SEALs comes from firing their own weapons, not from enemy action. The damage pattern suggested that years of training intended to make SEALs exceptional was leaving some barely able to function.
But the message Lieutenant Metcalf sent never got through to the Navy. No one at the lab told the SEAL leadership what the analysis had found, and the leadership never asked.
It was not the first time, or the last. At least a dozen Navy SEALs have died by suicide in the last 10 years, either while in the military or shortly after leaving. A grass-roots effort by grieving families delivered eight of their brains to the lab, an investigation by The New York Times has found. And after careful analysis, researchers discovered blast damage in every single one.
Evidence suggests that the damage may be just as widespread in SEALs who are still alive. A Harvard study, published this spring, scanned the brains of 30 career Special Operators and found an association between blast exposure and altered brain structure and compromised brain function. The more blast exposure the men had experienced, the more problems they reported with health and quality of life.
There are signs that the damage can come from a wide array of weapons. Artillery crew members who fired thousands of rounds in combat came home plagued by hallucinations and psychosis. Mortar teams suffered from headaches and deteriorating memory. Reliable soldiers suddenly turned violent and murdered neighbors after years of working around the blasts from tanks and grenades in combat or in training.
Blast waves may kill brain cells without causing any immediately noticeable symptoms, according to Dr. Daniel Daneshvar, chief of brain injury rehabilitation at Harvard Medical School.
“People may be getting injured without even realizing it,” Dr. Daneshvar said. “But over time, it can add up. People’s brains can often compensate until injuries accumulate to a critical level, he said; then, “people kind of fall off a cliff.”
In many cases, doctors treating the injured troops give them diagnoses of psychiatric disorders that miss the underlying physical damage. Much of what is categorized as post-traumatic stress disorder may actually be caused by repeated exposure to blasts.
The stories of the SEALs who died by suicide point to a troubling pattern in the elite force. Around the age of 40, nearly all of them started to struggle with insomnia and headaches, memory and coordination problems, depression, confusion and, sometimes, rage.Recent studies suggest that damage is caused when energy waves surging through the brain bounce off tissue boundaries like an echo, and for a few fractions of a millisecond, create a vacuum that causes nearby liquid in the brain to explode into bubbles of vapor. Those tiny explosions are violent enough to blow brain cells apart in a process known as cavitation.