Recent research shows mounting evidence of a link between mild traumatic brain injury and mental health conditions like depression, anxiety, and posttraumatic 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 mTBI 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.