Page 53 - JSOM Winter 2023

when developing diagnostic tests for SOF personnel who are succeed despite pain and discomfort is an essential component
exposed to both blasts and high altitudes. Similarly, Navy of SOF selection.
SEALs, Air Force Special Tactics Teams, Green Beret Combat
Dive Teams, and other Operators who perform combat div- Beyond the understandable reluctance of Operators to seek
ing, as well as Explosive Ordnance Disposal specialists who medical care that could lead to missing training or deployment
perform deep diving, may be at risk for a broad spectrum of is their potential hesitancy to call attention to symptoms that
neurological symptoms and electrophysiological alterations are perceived as mental rather than physical. The implications
associated with diving. 61 of the “invisible wounds of war” for individual Operators, and
for the military more broadly, have been widely discussed in
81
Additional exposures include vibrations and g-forces expe- opinion articles and policy statements. There have been ex-
rienced by Special Operations Aviation elements, Air Force tensive efforts by the U.S. Special Operations Command and
Combat Search and Rescue Operators, and Special Tactics Air- the U.S. Department of Defense to raise awareness about these
men, as well as rapid acceleration-deceleration forces experi- invisible wounds and to provide support for the millions of
82
enced by Naval Special Warfare Combatant-craft Crewmen as military personnel who have experienced TBI and PTSD. The
they travel over various sea-state conditions at high speed. 62-64 creation of centers of excellence that provide care for mili-
Finally, the physical and emotional stress of repeated expo- tary personnel with TBI and PTSD is emblematic of these ef-
sure to combat and the continuous threat of harm may lead forts. 83-85 However, most SOF personnel do not routinely seek
to symptoms and brain alterations that resemble those related these services early in their careers, when symptoms may have
to blast exposure. 65-67 The current inability to differentiate the best chance of responding to therapies. 86
the effects of these myriad exposures on the brain is a major
motivation for the development of blast-specific diagnostic Development and Deployment of a
biomarkers.
New Diagnostic Test for SOF Personnel
Logistical Barrier – Deployment of Operational Definitions of rBBI and Recovery
Diagnostic Tests to Combat Zones A foundational step toward development of a diagnostic
Diagnostic testing protocols for rBBI will need to be adaptable test for rBBI is to define rBBI itself. Despite recent efforts to
to the relative needs and conditions of training and combat. standardize terminology describing blast exposure, there are
During training, utilization of state-of-the-art, large-scale in- currently no standardized criteria that define a brain injury re-
46
frastructure –such as MRI and positron emission tomography sulting from RBE. Conceptually, rBBI is a brain injury caused
(PET) scanners – may be feasible. Hence, optimization of diag- by the cumulative effects of multiple blast overpressure events,
nostic test performance may involve leveraging these imaging many of which do not meet the U.S. Department of Defense/
technologies, which have shown promise in multiple observa- Department of Veterans Affairs criteria for a TBI. Operation-
4
tional studies over the past two decades. 23,68-70 The potential ally, we propose a definition of rBBI as a quantitative change

diagnostic utility of MRI and PET biomarkers in U.S. SOF in a blood or neuroimaging biomarkerthat exceeds the reliable
personnel is being tested in the ReBlast Pilot study, which was change index for that biomarker and is associated with RBE
designed to inform and accelerate efforts to develop a diagnos- during the same time period. 87
tic test for rBBI. 71
Using this working definition of rBBI, a diagnostic test should
In combat, an essential requirement of a diagnostic test for classify individual Operators into one of four groups:
rBBI is its deployability. To meet this requirement, a test must
be portable, compact, rugged, and secure and provide real-time • No rBBI: No evidence of rBBI, regardless of the extent of
feedback. These stipulations rule out brain MRI and PET scans, blast exposure or the presence of new physical symptoms,
which are not feasible to deploy in theater at scale. Technolo- cognitive deficits, or psychological health changes. We antic-
gies that could be deployable in theater include point-of-care ipate that symptoms observed in this group may be driven
blood tests, application-based cognitive performance tests, by comorbid psychological illness (e.g., PTSD), while ac-
electronically delivered and scored symptom questionnaires, knowledging the potential for false negatives (e.g., currently
and targeted neurological examinations (i.e., mental status, available neuroimaging and blood biomarkers may lack
cranial nerves, sensory/motor function, reflexes). 72-74 These sensitivity to detect rBBI in this group).

tests are being assessed for their diagnostic utility in multiple • Asymptomatic rBBI: Evidence of rBBI but absence of new
ongoing studies of blast TBI in military personnel, which in- physical symptoms, cognitive deficits, and psychological
clude EVOLVE, LETBI, LIMBIC-CENC, ENIGMA, ReBlast, health changes. A lack of measurable symptoms in this
and INVICTA. 71,75-79 It remains to be determined which tests, group may represent “false negatives” (e.g., currently avail-
alone or in combination, will provide the greatest sensitivity able self-reported and performance-based measures may
and specificity for detecting rBBI in training and combat. lack sensitivity to detect subtle changes in symptoms, or
Operators may under-report symptoms).
Social Barrier – Acknowledging Symptoms and • Symptomatic rBBI: Evidence of rBBI and development of
Seeking Care in a Culture of Self-Sacrifice and Fortitude new physical symptoms, cognitive deficits, or psychological
Though empiric evidence about SOF attitudes toward their health changes.
own health care is limited, public interviews with SOF per- • Recovery from rBBI: Evidence of rBBI and resolution of
sonnel suggest that commitment to the team and mission is physical symptoms, cognitive deficits, or psychological
prioritized over personal health and safety. 22,80 It is therefore health changes that were detected at an earlier assessment.
not surprising that many Operators are willing to train and
deploy even when they are experiencing physical, cognitive, or Accurate classification requires careful baselining to deter-
psychological symptoms. Indeed, the ability to persevere and mine pre-exposure biomarker levels and serial assessment to

Brain Health in U.S. Special Operations Forces | 51