Recent research shows mounting evidence of a link between mild traumatic brain injury and mental health conditions like depression, anxiety, and post-traumatic stress disorder.
For the first time, a study of post-mortem brains of service members who were diagnosed with blast-related concussions found visible evidence of damage to the brain.
Researchers believe the unique scarring that the study found could account for the mental health conditions that are diagnosed more frequently among service members who have suffered mild TBIs or been exposed to blast concussions.
In other words, the "invisible wounds" - as TBI is frequently called - might not be invisible anymore.
"The more we look, the more we're finding other subtleties and other kinds of changes in the brains of individuals who've been exposed to blast," said Dr. Daniel Perl, one of the study's researchers and a neuropathologist specializing in TBI and neurodegeneration at the Uniformed Services University (USU) of the Health Sciences in Bethesda, Maryland.
As a result, "we think there is a biology to this, that the exposure to blast can, in some people, produce damage to the brain, which leads to dysfunction and underlies some aspects of (mental health issues)," Perl said.
THE LINK
TBI is associated with an increased risk of psychological health conditions, such as anxiety, depression, and even post-traumatic stress, according to experts at the Defense Health Agency's Traumatic Brain Injury Center of Excellence (TBICoE), in Falls Church, Virginia.
A 2019 study of a Department of Veterans Affairs health care database found that "a history of TBI increased the risk for suicide and other psychiatric conditions by more than two-fold."
Veterans with a history of TBI also had a two-to-four times higher prevalence of psychiatric diagnoses compared with those who did not suffer a TBI, with PTSD being the most common, according to the TBICoE team.
The prevalence of depression in the TBI group was 68.1 percent, the TBICoE team said.
David Riggs, a clinical psychologist and chair of the Department of Medical and Clinical Psychology at USU, explained how the exact reason for the neuropsychiatric symptoms service members experience following a blast-related concussion is not clear.
"We don't know exactly, particularly in the case of mild TBIs or concussions, what might be leading to these problems because it's very hard to identify the specific change in the way that the brain functions after a concussion," he said.
"If you have a penetrating head injury, where the skull is fractured or penetrated, you can actually identify the part of the brain that was injured and perhaps is no longer functioning at all," added Riggs.
"In the case of concussion, it's very hard to identify where the brain was injured."
Riggs explained that there might be a disruption in "the way that the neurons in the brain talk to one another."
What is known, is "that the way that a person processes information is related to mood and trauma symptoms on the psychological or psychiatric side," said Riggs. "So, it may be that there are disruptions at the neurological level that lead to these psychological and psychiatric issues."
"It's also possible that what leads to the depression or the trauma symptoms isn't about the injury, the concussion, or the idea that the brain is working differently, but rather the emotional and life-disrupting aspects of that," he added.
SEEING THE ‘INVISIBLE WOUNDS'?
Mild TBI occurs when there's a sudden jolt to the head due to impact or blast, causing it and the brain to jerk abruptly back and forth. This results in the brain bouncing or twisting inside the skull, creating chemical changes that can stretch and harm the brain cells, thus affecting brain function, according to the Centers for Disease Control and Prevention.
While the USU study appears to have identified physical scars from blast damage in service members who are deceased, there are no visible damages to the brain when testing live patients diagnosed with blast-related concussion and other forms of TBI.
"When you do an MRI on such a patient, you don't see anything consistently," said Perl. "The implication is that something's wrong with the brain, but you just can't see it."
Perl established a neuropathology lab at USU dedicated to researching the acute and long-term effects of TBI and PTSD among military personnel. In the study, they analyzed brain specimens of cases with chronic blast exposure, acute blast exposure, chronic impact TBI, exposure to opiates, and a control group with no known neurological disorders for comparison.
"The one thing that kept coming up in these cases (with blast exposure) was a pattern of scarring in the brain that seemed rather unique and had really not been described previously," he said.
"And the more we worked, the more it appeared to be related to blast exposure."
The type of unique scarring they observed is called interface astroglial scarring. From there, they learned that blast waves emerging from detonations of high explosives such as improvised explosive devices and suicide bombs carry pressure waves "that expand in all different directions, at about the speed of sound, and actually pass through the skull, and through the brain, the most delicate and complex organ in the body," he said.
This led to the assumption that it must produce some damage to the brain.
"Indeed, the places where we found the scarring were places where biophysicists had previously shown that the blast wave gives off its energy," he said. "Putting two and two together, we have indicated that we think that the blast wave is damaging the brain in these locations, and this is the brain's attempt to repair itself from that damage."
"Mental health issues may be superimposed to this," he said, attributing the symptoms of concussion to "a duality of both factors - biologic factors plus functional factors - that are interplaying, interacting."
SIMILAR SYMPTOMS
Concussion can result in a wide variety of symptoms that can also be attributed to other causes, including headaches, irritability, fatigue, balance difficulties, sleep disturbance, dizziness, ringing in the ears, blurred vision, concentration, or memory difficulties, and other problems. But these are believed to be temporary and usually heal on their own over time, as the brain resettles back to regular functioning.
Likewise, people who have had a TBI and people who are depressed can share similar symptoms. These include low activity levels, sleep problems, difficulty controlling emotions, loss of interest in pleasurable activities, decreased energy, changes in appetite, and lack of initiation.
Similarly, Riggs said, while some people with a concussion may also have PTSD, not everyone does. He said some experts believe some people may be more vulnerable to psychological health conditions after a concussion because they were having problems already, or because they may be genetically predisposed to psychological health issues, like depression or anxiety.
Either way, the psychological health conditions that arise from concussions may require longer-term treatment.
Common treatment options include counseling and medications. Most cases of PTSD respond well to treatment, according to TBICoE.
And some complementary or alternative medical approaches such as meditation have shown to be useful, as a second-line treatment for managing PTSD.
Perl's research findings have implications for the way TBI might be diagnosed and treated in the future as well as for spurring broader research on the ways service members can be better protected as they head into situations where they might be exposed to blasts.
"We're beginning to work on if there are means by which we can detect this in living individuals," said Perl. "Our work has stimulated a number of ongoing studies to look for unique ways in which newer imaging and even fluid biomarkers can be used to identify these changes in the living."
Service members experiencing depression, anxiety, and PTSD due to concussion are not alone. The TBICoE website provides ample resources to help service members, veterans, their families, and loved ones cope with mTBI.
If you notice changes in the behavior of a loved one after concussion or fear a loved one may try to hurt themselves, urge them to call their health care provider, the National Suicide Prevention Lifeline at 800-273-8255 (TALK), or the Military Crisis Line at 800-273-8255 as soon as possible.