Table 1.

A summary of clinical studies. mTBI = mild traumatic brain injury; LOC = loss of consciousness; AMS = altered mental status/altered mental state; MDD = major depressive disorder; PTSD = post-traumatic stress disorder; ANAM = Automated Neuropsychological Assessment Metric; AOC = alteration of consciousness; EMED = Expeditionary Medical Encounter Database; PCS = post-concussive/post-concussion syndrome; ASR = acute stress reaction; FA= fractional anisotropy; QoL = quality of life; CLSA = Canadian Longitudinal Study on Aging; PM = prospective memory; IL-6 = interleukin 6; PTA = post-traumatic amnesia; NSI = neurobehavioral symptom inventory; HeadSMART = Head injury Serum Markers for Assessing Response to Trauma; AST = attention switching task; rACC = rostral anterior cingulate cortex; MS-TBI = moderate-to-severe TBI; SSD = somatic symptom disorder.

Author, Year	Patient Population	Nature/Cause of Injury	Timing of Assessment	Groups	Outcomes
Hoge et al., 2008 [10]	Soldiers returning frrom Iraq	Blast or explosion, bullet, fragment or shrapnel, fall, vehicle accident, other	3–4 months after deployment	mTBI with LOC mTBI with AMS Other injury No injury	LOC associated with headache, MDD, PTSD
Luethcke et al., 2011 [11]	Military personnel and civilian contractors in Iraq	Blast injury, non-blast injury (blunt object, sport/recreation, falls, motor vehicle accident)	Within 72 h of injury	Blast mTBI Non-blast mTBI No LOC LOC >1 min LOC 1–20 min LOC <20 min	LOC duration correlated with greater decline in ANAM accuracy scores between baseline and post-injury tests
Wilk et al., 2012 [12]	Soldiers returning from Afghanistan and Iraq	Blast/explosion, bullet, fragment/shrapnel, fall, vehicle crash, or other	4–6 months after deployment	Single AOC Single LOC Multiple AOC Multiple (1+) LOC Other injuries No injury	LOC associated with MDD, PTSD, headache, memory problems, balance problems, muskulosekeltal pain
Eskridge et al., 2013 [13]	Retrospective study of male service members in Iraq from the EMED	Blast-related injury	mTBI diagnosed within 48 h of injury; variable follow-up	mTBI with LOC mTBI without LOC	LOC associated with PTSD and PCS
Roitman et al., 2013 [14]	Motor vehicle accident survivors	Motor vehicle accident	Admission average of 1.5 h after the accident; PTSD evaluation 10 days and 8 months later	LOC Head injury No head injury	LOC associated with elevated PTSD scores at 10 days and 8 months vs. head injury and no head injury groups; elevated PTSD prevalence and re-experiencing/intrusion cluster scores 8 months post-injury
Sorg et al., 2014 [15]	Afghanistan and Iraq war veterans	Blunt or blast injury	Variable	mTBI with LOC mTBI with AOC Controls	LOC associated with reduced executive functioning, reduced ventral prefrontal white matter integrity
Norris et al., 2014 [16]	Military personnel in Afghanistan	Blast-related injury	mTBI diagnosis within 72 h of injury; follow-up 48–72 h later	mTBI with LOC mTBI without LOC	LOC associated with ASRs, memory problems, hearing loss, difficulty sleeping, increased symptom reporting
Hayes et al., 2015 [17]	Afghanistan and Iraq war veterans	Blast-related injury	Variable	mTBI with LOC mTBI without LOC Controls	Lower internal capsule FA associated with greater PTSD symptom severity in LOC group
Sofko et al., 2016 [18]	Afghanistan and Iraq war veterans	Fragments, bullets, vehicular accidents, falls or blasts	Shortly following intake for PTSD treatment	mTBI with LOC mTBI without LOC	LOC associated with avoidance, lower psychological QoL, and more post-concussive symptoms
Bedard et al., 2018 [19]	mTBI patients from CLSA cohort	Not specified	1 year or more after mTBI	LOC <1 min LOC 1–20 min Controls	LOC 1–20 min associated with worse performance on event-based PM tasks compared to LOC < 1 min, but not compared to controls; both LOC groups had impairments in time-based PM tasks
Kanefsky et al., 2019 [20]	Active duty military personnel recruited from sleep study cohort	Not specified	3–18 months after returning from deployment	mTBI with LOC mTBI without LOC Controls	LOC associated with higher pain self-reporting and higher levels of plasma IL-6
Bedard et al., 2020 [21]	mTBI patients from CLSA cohort	Not specified	1 year or more after mTBI	LOC < 1 min LOC 1–20 min Controls	LOC 1–20 min associated with higher impairment rates in declarative memory and executive functioning tasks
Gray et al., 2020 [22]	Retrospective study of veterans from Polytrauma Network Site	Blasts, motor vehicle accidents, falls, blunt trauma	Variable	Men or women mTBI with LOC mTBI with AOC mTBI with PTA	-LOC duration correlated with loss of balance, poor coordination, fatigue, worse vestibular score on NSI in women -LOC duration correlated with less forgetfulness and better cognitive score on NSI in men
Roy et al., 2020 [23]	mTBI patients from HeadSMART cohort	Blunt head trauma by pedestrian struck, motor vehicle collision, fall, assault, struck by or against and object, bicycle collision, other, intoxication by drugs or alcohol	Medically evaluated within 24 h of mTBI; functional recovery assessed 1, 3, 6 months after TBI	AMS only LOC only LOC and AMS Neither LOC nor AMS	LOC associated with incomplete functional recovery 1 and 3 months after injury
Arciniega et al., 2020 [24]	Undergraduate students with mTBI	Closed-head injury from non-sport causes or individual, high-impact, or team sports	Average of 4 years after injury	mTBI with LOC mTBI without LOC Controls	LOC associated with better visual working memory
Vanier et al., 2020 [25]	mTBI patients in litigation for brain injury	Motor vehicle accidents, fall, assault, other	Variable	mTBI with LOC mTBI without LOC	LOC associated with balance problems, MDD, fatigue, emotional lability, headache, cognitive deficits with slow recovery
Karlsen et al., 2021 [26]	mTBI patients in Trondheim mTBI follow-up study	Fall, violence, bicycle, sport motor vehicle accident, struck object, other	Approximately 2 weeks following mTBI	mTBI with LOC mTBI without LOC Community controls Trauma controls	LOC associated with lower congruence cost (better performance) on AST
Shahrestani et al., 2022 [27]	Retrospective cohort analysis of mTBI patients from Nationwide Readmission Database	Not specified	Followed until readmission within 180 days after primary admission	mTBI with LOC mTBI without LOC Male or female Age <26, 26–50, 51–75, >75 years old	LOC patients had higher rates of MDD in all groups, age- and sex-dependent increases in anxiety and suicidal ideation
Kosaraju et al., 2022 [28]	mTBI patients from trauma center study of serum biomarkers and PTSD	Interpersonal, motor vehicle accident, other	Enrolled at initial ED visit; PTSD symptom evaluation 1, 3, 6, 12 months after enrollment	mTBI with LOC mTBI without LOC	LOC associated with chronic PTSD profile, thickness in left and right rACC
Kim et al., 2023 [29]	mTBI or MS-TBI service members in Iraq and Afghanistan	Not specified	Initial intake within a few days of injury, initial assessment up to 72 h later, follow-ups 0–75 days (AP1) and 90–365 days (AP2) post-injury	mTBI with LOC mTBI without LOC MS-TBI Non-TBI	mTBI with LOC associated with: -higher MDD and SSD vs. mTBI without LOC -higher PTSD, MDD, and SSD vs. non-TBI