Head injury and combat-related posttraumatic stress disorder

Association of War Zone-Related Stress With Alterations in Limbic Gray Matter Microstructure

IMPORTANCE

Military service members returning from theaters of war are at increased risk for mental illness, but despite high prevalence and substantial individual and societal burden, the underlying pathomechanisms remain largely unknown. Exposure to high levels of emotional stress in theaters of war and mild traumatic brain injury (mTBI) are presumed factors associated with risk for the development of mental disorders.

OBJECTIVE

To investigate (1) whether war zone-related stress is associated with microstructural alterations in limbic gray matter (GM) independent of mental disorders common in this population, (2) whether associations between war zone-related stress and limbic GM microstructure are modulated by a history of mTBI, and (3) whether alterations in limbic GM microstructure are associated with neuropsychological functioning.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was part of the TRACTS (Translational Research Center for TBI and Stress Disorders) study, which took place in 2010 to 2014 at the Veterans Affair Rehabilitation Research and Development TBI National Network Research Center. Participants included male veterans (aged 18-65 years) with available diffusion tensor imaging data enrolled in the TRACTS study. Data analysis was performed between December 2017 to September 2021.

EXPOSURES

The Deployment Risk and Resilience Inventory (DRRI) was used to measure exposure to war zone-related stress. The Boston Assessment of TBI-Lifetime was used to assess history of mTBI. Stroop Inhibition (Stroop-IN) and Inhibition/Switching (Stroop-IS) Total Error Scaled Scores were used to assess executive or attentional control functions.

MAIN OUTCOMES AND MEASURES

Diffusion characteristics (fractional anisotropy of tissue [FAT]) of 16 limbic and paralimbic GM regions and measures of functional outcome.

RESULTS

Among 384 male veterans recruited, 168 (mean [SD] age, 31.4 [7.4] years) were analyzed. Greater war zone-related stress was associated with lower FAT in the cingulate (DRRI-combat left: P = .002, partial r = -0.289; DRRI-combat right: P = .02, partial r = -0.216; DRRI-aftermath left: P = .004, partial r = -0.281; DRRI-aftermath right: P = .02, partial r = -0.219), orbitofrontal (DRRI-combat left medial orbitofrontal cortex: P = .02, partial r = -0.222; DRRI-combat right medial orbitofrontal cortex: P = .005, partial r = -0.256; DRRI-aftermath left medial orbitofrontal cortex: P = .02, partial r = -0.214; DRRI-aftermath right medial orbitofrontal cortex: P = .005, partial r = -0.260; DRRI-aftermath right lateral orbitofrontal cortex: P = .03, partial r = -0.196), and parahippocampal (DRRI-aftermath right: P = .03, partial r = -0.191) gyrus, as well as with higher FAT in the amygdala-hippocampus complex (DRRI-combat: P = .005, partial r = 0.254; DRRI-aftermath: P = .02, partial r = 0.223). Lower FAT in the cingulate-orbitofrontal gyri was associated with impaired response inhibition (Stroop-IS left cingulate: P < .001, partial r = -0.440; Stroop-IS right cingulate: P < .001, partial r = -0.372; Stroop-IS left medial orbitofrontal cortex: P < .001, partial r = -0.304; Stroop-IS right medial orbitofrontal cortex: P < .001, partial r = -0.340; Stroop-IN left cingulate: P < .001, partial r = -0.421; Stroop-IN right cingulate: P < .001, partial r = -0.300; Stroop-IN left medial orbitofrontal cortex: P = .01, partial r = -0.223; Stroop-IN right medial orbitofrontal cortex: P < .001, partial r = -0.343), whereas higher FAT in the mesial temporal regions was associated with improved short-term memory and processing speed (left amygdala-hippocampus complex: P < .001, partial r = -0.574; right amygdala-hippocampus complex: P < .001, partial r = 0.645; short-term memory left amygdala-hippocampus complex: P < .001, partial r = 0.570; short-term memory right amygdala-hippocampus complex: P < .001, partial r = 0.633). A history of mTBI did not modulate the association between war zone-related stress and GM diffusion.

CONCLUSIONS AND RELEVANCE

This study revealed an association between war zone-related stress and alteration of limbic GM microstructure, which was associated with cognitive functioning. These results suggest that altered limbic GM microstructure may underlie the deleterious outcomes of war zone-related stress on brain health. Military service members may benefit from early therapeutic interventions after deployment to a war zone.

Mild traumatic brain injury impacts associations between limbic system microstructure and post-traumatic stress disorder symptomatology

BACKGROUND

Post-traumatic stress disorder (PTSD) is a psychiatric disorder that afflicts many individuals, yet the neuropathological mechanisms that contribute to this disorder remain to be fully determined. Moreover, it is unclear how exposure to mild traumatic brain injury (mTBI), a condition that is often comorbid with PTSD, particularly among military personnel, affects the clinical and neurological presentation of PTSD. To address these issues, the present study explores relationships between PTSD symptom severity and the microstructure of limbic and paralimbic gray matter brain regions, as well as the impact of mTBI comorbidity on these relationships.

METHODS

Structural and diffusion MRI data were acquired from 102 male veterans who were diagnosed with current PTSD. Diffusion data were analyzed with free-water imaging to quantify average CSF-corrected fractional anisotropy (FA) and mean diffusivity (MD) in 18 limbic and paralimbic gray matter regions. Associations between PTSD symptom severity and regional average dMRI measures were examined with repeated measures linear mixed models. Associations were studied separately in veterans with PTSD only, and in veterans with PTSD and a history of military mTBI.

RESULTS

Analyses revealed that in the PTSD only cohort, more severe symptoms were associated with higher FA in the right amygdala-hippocampus complex, lower FA in the right cingulate cortex, and lower MD in the left medial orbitofrontal cortex. In the PTSD and mTBI cohort, more severe PTSD symptoms were associated with higher FA bilaterally in the amygdala-hippocampus complex, with higher FA bilaterally in the nucleus accumbens, with lower FA bilaterally in the cingulate cortex, and with higher MD in the right amygdala-hippocampus complex.

CONCLUSIONS

These findings suggest that the microstructure of limbic and paralimbic brain regions may influence PTSD symptomatology. Further, given the additional associations observed between microstructure and symptom severity in veterans with head trauma, we speculate that mTBI may exacerbate the impact of brain microstructure on PTSD symptoms, especially within regions of the brain known to be vulnerable to chronic stress. A heightened sensitivity to the microstructural environment of the brain could partially explain why individuals with PTSD and mTBI comorbidity experience more severe symptoms and poorer illness prognoses than those without a history of brain injury. The relevance of these microstructural findings to the conceptualization of PTSD as being a disorder of stress-induced neuronal connectivity loss is discussed.

Sensory sensitivity and posttraumatic stress disorder in blast exposed veterans with mild traumatic brain injury

The purpose of this study was to examine the unique contribution of posttraumatic stress disorder (PTSD) symptoms on sensory sensitivity following mild traumatic brain injury (mTBI) in an Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) Veteran sample. We hypothesized that the effect of PTSD on noise and light sensitivity following mTBI would be largely driven by PTSD-related hyperarousal symptoms. We compared the relationships between PTSD, noise sensitivity, and light sensitivity of 49 OEF/OIF Veterans with mTBI to that of 23 OEF/OIF Veterans without mTBI. Results suggest that intrusive experiences were significantly related to noise sensitivity in the mTBI group, while light sensitivity was significantly associated with avoidance. Hyperarousal symptoms significantly accounted for noise sensitivity in the no-blast, non-TBI group, whereas PTSD did not affect light sensitivity in this group. These data suggest that PTSD symptoms may uniquely influence the experience of noise and light sensitivity. As such, treatment targeting specific PTSD symptoms may yield clinically significant improvement in sensory sensitivity.

[Formula: see text]Interpreting change on the neurobehavioral symptom inventory and the PTSD checklist in military personnel

OBJECTIVE

The purpose of this study was to examine the prevalence and stability of symptom reporting in a healthy military sample and to develop reliable change indices for two commonly used self-report measures in the military health care system.

PARTICIPANTS AND METHOD

Participants were 215 U.S. active duty service members recruited from Fort Bragg, NC as normal controls as part of a larger study. Participants completed the Neurobehavioral Symptom Inventory (NSI) and Posttraumatic Checklist (PCL) twice, separated by approximately 30 days.

RESULTS

Depending on the endorsement level used (i.e. ratings of 'mild' or greater vs. ratings of 'moderate' or greater), approximately 2-15% of this sample met DSM-IV symptom criteria for Postconcussional Disorder across time points, while 1-6% met DSM-IV symptom criteria for Posttraumatic Stress Disorder. Effect sizes for change from Time 1 to Time 2 on individual symptoms were small (Cohen's d = .01 to .13). The test-retest reliability for the NSI total score was r = .78 and the PCL score was r = .70. An eight-point change in symptom reporting represented reliable change on the NSI total score, with a seven-point change needed on the PCL.

CONCLUSIONS

Postconcussion-like symptoms are not unique to mild TBI and are commonly reported in a healthy soldier sample. It is important for clinicians to use normative data when evaluating a service member or veteran and when evaluating the likelihood that a change in symptom reporting is reliable and clinically meaningful.

Post-traumatic stress disorder and traumatic brain injury

Disentangling the effects of "organic" neurologic damage and psychological distress after a traumatic brain injury poses a significant challenge to researchers and clinicians. Establishing a link between traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) has been particularly contentious, reflecting difficulties in establishing a unique diagnosis for conditions with overlapping and sometimes contradictory symptom profiles. However, each disorder is linked to a variety of adverse health outcomes, underscoring the need to better understand how neurologic and psychiatric risk factors interact following trauma. Here, we present data showing that individuals with a TBI are more likely to develop PTSD, and that individuals with PTSD are more likely to develop persistent cognitive sequelae related to TBI. Further, we describe neurobiological models of PTSD, highlighting how patterns of neurologic damage typical in TBI may promote or protect against the development of PTSD in brain-injured populations. These data highlight the unique course of PTSD following a TBI and have important diagnostic, prognostic, and treatment implications for individuals with a dual diagnosis.

The mental health sequelae of traumatic head injury in South Vietnamese ex-political detainees who survived torture

Little is known about the relationship between traumatic head injury (THI) and psychiatric morbidity in torture survivors. We examine the relationship between THI and depression, PTSD, post-concussive syndrome (PCS), disability and poor health status in Vietnamese ex-political detainees who survived incarceration in Vietnamese re-education camps. A community sample of ex-political detainees (n=337) and a non-THI, non-ex-detainee comparison group (n=82) were surveyed. Seventy-eight percent of the ex-political detainees had experienced THI; 90.6% of the ex-political detainees and 3.6% of the comparison group had experienced 7 or more trauma events. Depression and PTSD were greater in ex-detainees than in the comparison group (40.9% vs 23.2% and 13.4% vs 0%). Dose-effect relationships for THI and trauma/torture in the ex-political detainee group were significant. Logistic regression in the pooled sample of ex-detainees and the comparison group confirmed the independent impact of THI from trauma/torture on psychiatric morbidity (OR for PTSD=22.4; 95% CI: 3.0-165.8). These results demonstrate important effects of THI on depression and PTSD in Vietnamese ex-detainees who have survived torture.

Effects of OEF/OIF-related physical and emotional co-morbidities on associative learning: concurrent delay and trace eyeblink classical conditioning

This study examined the performance of veterans and active duty personnel who served in Operation Enduring Freedom and/or Operation Iraqi Freedom (OEF/OIF) on a basic associative learning task. Eighty-eight individuals participated in this study. All received a comprehensive clinical evaluation to determine the presence and severity of posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI). The eyeblink conditioning task was composed of randomly intermixed delay and trace conditioned stimulus (CS) and unconditioned stimulus (US) pairs (acquisition) followed by a series of CS only trials (extinction). Results revealed that those with a clinical diagnosis of PTSD or a diagnosis of PTSD with comorbid mTBI acquired delay and trace conditioned responses (CRs) to levels and at rates similar to a deployed control group, thus suggesting intact basic associative learning. Differential extinction impairment was observed in the two clinical groups. Acquisition of CRs for both delay and trace conditioning, as well as extinction of trace CRs, was associated with alcoholic behavior across all participants. These findings help characterize the learning and memory function of individuals with PTSD and mTBI from OEF/OIF and raise the alarming possibility that the use of alcohol in this group may lead to more significant cognitive dysfunction.

PTSD modifies performance on a task of affective executive control among deployed OEF/OIF veterans with mild traumatic brain injury

Individuals with post-traumatic stress disorder (PTSD) show a cognitive bias for threatening information, reflecting dysregulated executive control for affective stimuli. This study examined whether comorbid mild Traumatic Brain Injury (mTBI) with PTSD exacerbates this bias. A computer-administered Affective Go/No-Go task measured reaction times (RTs) and errors of omission and commission to words with a non-combat-related positive or negative valence in 72 deployed United States service members from the wars in Iraq and Afghanistan. Incidents of military-related mTBI were measured with the Boston Assessment of Traumatic Brain Injury-Lifetime. PTSD symptoms were measured with the Clinician-Administered PTSD Scale. Participants were divided into those with (mTBI+, n = 34) and without a history of military-related mTBI (mTBI-, n = 38). Valence of the target stimuli differentially impacted errors of commission and decision bias (criterion) in the mTBI+ and mTBI- groups. Specifically, within the mTBI+ group, increasing severity of PTSD symptoms was associated with an increasingly liberal response pattern (defined as more commission errors to negative distractors and greater hit rate for positive stimuli) in the positive compared to the negative blocks. This association was not observed in the mTBI- group. This study underscores the importance of considering the impact of a military-related mTBI and PTSD severity upon affective executive control.

Detection of blast-related traumatic brain injury in U.S. military personnel

BACKGROUND

Blast-related traumatic brain injuries have been common in the Iraq and Afghanistan wars, but fundamental questions about the nature of these injuries remain unanswered.

METHODS

We tested the hypothesis that blast-related traumatic brain injury causes traumatic axonal injury, using diffusion tensor imaging (DTI), an advanced form of magnetic resonance imaging that is sensitive to axonal injury. The subjects were 63 U.S. military personnel who had a clinical diagnosis of mild, uncomplicated traumatic brain injury. They were evacuated from the field to the Landstuhl Regional Medical Center in Landstuhl, Germany, where they underwent DTI scanning within 90 days after the injury. All the subjects had primary blast exposure plus another, blast-related mechanism of injury (e.g., being struck by a blunt object or injured in a fall or motor vehicle crash). Controls consisted of 21 military personnel who had blast exposure and other injuries but no clinical diagnosis of traumatic brain injury.

RESULTS

Abnormalities revealed on DTI were consistent with traumatic axonal injury in many of the subjects with traumatic brain injury. None had detectable intracranial injury on computed tomography. As compared with DTI scans in controls, the scans in the subjects with traumatic brain injury showed marked abnormalities in the middle cerebellar peduncles (P<0.001), in cingulum bundles (P=0.002), and in the right orbitofrontal white matter (P=0.007). In 18 of the 63 subjects with traumatic brain injury, a significantly greater number of abnormalities were found on DTI than would be expected by chance (P<0.001). Follow-up DTI scans in 47 subjects with traumatic brain injury 6 to 12 months after enrollment showed persistent abnormalities that were consistent with evolving injuries.

CONCLUSIONS

DTI findings in U.S. military personnel support the hypothesis that blast-related mild traumatic brain injury can involve axonal injury. However, the contribution of primary blast exposure as compared with that of other types of injury could not be determined directly, since none of the subjects with traumatic brain injury had isolated primary blast injury. Furthermore, many of these subjects did not have abnormalities on DTI. Thus, traumatic brain injury remains a clinical diagnosis. (Funded by the Congressionally Directed Medical Research Program and the National Institutes of Health; ClinicalTrials.gov number, NCT00785304.).

Drowning in the bible and contemporary society: responsibilities of religious caregivers

The aim of this study was to research drowning incidents and rescues that are included in the Bible and provide recommendations for how religious caregivers can support psychologically affected victims. Results confirm that the Bible contains six aquatic emergencies. Persons threatened with drowning were saved by an act of God, a human act and acts of human/divine interaction, when, for example, a person was ordered by God to perform an action which resulted in saving people on the threshold of drowning. The drowning casualties were largely individual males and some cases with multiple victims (male and female) as well. The outcomes of the drowning incidents were the survival of most of the casualties whose stories are told in the Bible. One person is reported to have drowned. Drowning incidents occurred at sea and on earth. The types of rescues used were reach-rescue and rescue and survival. The drowning casualties were rescued from land and from ships and boats by human rescuers. Some rescues were achieved by divine miracles.

Predictors of emotional distress reported by soldiers in the combat zone

OBJECTIVE

Few studies have examined rates of distress of military personnel during deployment to a war zone. Our study sought to (a) identify rates of self-reported posttraumatic stress disorder (PTSD) and depression symptoms during combat deployment, (b) characterize higher order dimensions of emotional distress experienced by soldiers during deployment, and (c) identify predictors of these dimensions of emotional distress.

METHOD

Participants were 2677 National Guard soldiers deployed as part of Operation Iraqi Freedom in 2006-07. We performed a principal components factor analysis on items of the PTSD Checklist - Military Version and the Beck Depression Inventory to identify dimensions of emotional distress, followed by multiple regression analyses to identify factors that predicted these dimensions of distress.

RESULTS

Rates of PTSD and depression in our sample were 7% and 9%, respectively. Five dimensions of emotional distress emerged: negative affect/cognitions, trauma-specific re-experiencing and avoidance, vegetative symptoms, loss of interest/numbing symptoms, and arousal/irritability. Two dimensions, trauma-specific symptoms and arousal/irritability, appeared to be more indicative of trauma sequelae, while the other three dimensions were more indicative of depressive symptoms. Demographic factors, combat exposure (including injury and exposure to explosive blast), and attitudinal variables predicted trauma-specific aspects of distress. Symptoms characteristic of depression or generalized distress were predicted by female gender, recent prior deployment, and attitudinal factors but were not predicted by blast exposure or injury.

CONCLUSIONS

These findings suggest specific targets for contextual and individual interventions to reduce deployment-related distress and point out the need for longitudinal follow-up to determine long-term implications for post-deployment functioning.

Mild traumatic brain injury and posttraumatic stress disorder in returning veterans: perspectives from cognitive neuroscience

A significant proportion of military personnel deployed in support of Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) has been exposed to war-zone events potentially associated with traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD). There has been significant controversy regarding healthcare policy for those service members and military veterans who returned from OEF/OIF deployments with both mild TBI and PTSD. There is currently little empirical evidence available to address these controversies. This review uses a cognitive neuroscience framework to address the potential impact of mild TBI on the development, course, and clinical management of PTSD. The field would benefit from research efforts that take into consideration the potential differential impact of mild TBI with versus without persistent cognitive deficits, longitudinal work examining the trajectory of PTSD symptoms when index trauma events involve TBI, randomized clinical trials designed to examine the impact of mild TBI on response to existing PTSD treatment interventions, and development and examination of potential treatment augmentation strategies.

Effects of appraisal and coping on the neuroendocrine response to extreme stress

Although many people are exposed to extreme stress, only some of them develop psychobiological disturbances that can lead to posttraumatic stress disorder (PTSD) or other posttrauma psychopathology. This paper examines the effects of different types of appraisal and coping to find clues to how individuals differ in their neuroendocrine responses to extreme stress. It proposes a conceptual model for components of the adult response to stressors. Threat appraisal and defensive coping may play crucial roles in determining the neuroendocrine response to trauma with potential mental health consequences, particularly PTSD.

[Comorbidity of posttraumatic stress disorder and mild closed head injury in war veterans: endocrinological and psychological profiles]

AIM

To determine the degree of psychological and endocrinological changes in war veterans with the diagnosis of Chronic Posttraumatic Stress Disorder (PTSD) regarding presence/absence of comorbid mild closed head injury (mCHI) caused by explosive devices.

METHODS

Two groups of PTSD inpatients, with (n = 37), and without (n = 86) sustained blast trauma followed by mCHI were formed during the psychiatric treatment. Participants were interviewed by experienced clinicians who used the PTSD Interview (PTSD-I). In addition, patients completed the Symptom Checklist-90-Revised (SCL-90-R). Serum levels of ten hormones were assessed: triiodothyronine, thyroxine, thyrotropin-stimulating hormone, prolactin, luteinizing hormone, follicle-stimulating hormone, and insulin, by radioimmunoassays and hydrocortisone, growth hormone and testosterone by fluoroimmunoassays.

RESULTS

Veterans with comorbid mCHI and PTSD showed significantly higher level of amnesia for traumatic event as well as of somatization on the SCL-90-R. Significant differences of hormone levels were not found.

CONCLUSION

The results didn't support the hypothesis on specific PTSD subgroup characterized by history of mCHI and consecutive postconcussion syndrome. The absence of differences in levels of hormones indicated the dominant role of psychogenic trauma in the etiology of hormone disbalance in chronic PTSD. Amnesia for traumatic event in war veterans with comorbid PTSD and mCHI was easily explained by neurogenic peritraumatic amnesia due to the blast trauma, but it did not affect either quality of intensity or posttraumatic symptoms as well as endocrinological parameters.

Attention, learning, and memory performances and intellectual resources in Vietnam veterans: PTSD and no disorder comparisons

Attention, learning, memory, and estimated intellectual potential were examined in 26 Vietnam veterans diagnosed with posttraumatic stress disorder (PTSD) and in 21 Vietnam veterans without mental disorders. Results revealed PTSD-associated cognitive deficits on tasks of sustained attention, working memory, initial learning, and estimated premorbid intelligence but not on measures of focus of attention, shift of attention, or memory savings. Cognitive task performances adjusted for estimated native intelligence remained negatively correlated with PTSD severity. An intellectual measure adjusted for cognitive task performances was negatively correlated with PTSD severity, even after the authors statistically controlled the level of combat exposure. Results suggested that although intellectual resources may constitute a vulnerability-protective factor for PTSD development, PTSD was associated with cognitive impairment independent of intellectual functioning.

Function after motor vehicle accidents: a prospective study of mild head injury and posttraumatic stress

Relationships among mild traumatic brain injury (MTBI), posttraumatic stress (PTS), and function were examined in 99 motor vehicle accident (MVA) admissions: 64 in an MTBI group and 35 in a no-MTBI comparison group. Assessments occurred within the first month and at 6 to 9 months. At follow-up, the sample was moderately disabled on the Sickness Impact Profile (SIP), 71% satisfied on the Reintegration of Normal Living Index (RNL), and 42% had returned to work. Only the SIP Psychosocial score was significantly different for MTBI groups; 24% of the sample showed definite symptoms of PTS. This group was significantly more disabled on the SIP, less satisfied on the RNL, and less likely to return to work. The proportion of variance in outcome explained in each model ranged from 32% (Physical SIP) to 44% (RNL). Results suggest the need for clinicians to be more aware of the strong influence of PTS on functional outcomes.

Contribution of PTSD/POW history to behavioral disturbances in dementia

As many World War II and Korean Conflict veterans suffering from posttraumatic stress disorder (PTSD) grow older, increasing numbers will be diagnosed with dementia. We retrospectively analyzed patients with dementia, comparing the behavioral disturbances of those with PTSD to those without PTSD. We hypothesized that due to the additive effect of the neurobiological and behavioral changes associated with PTSD and dementia, the dementia with PTSD group would show more agitation and disinhibition than the dementia without PTSD group. Sixteen patients with diagnoses of dementia and PTSD were matched on age and Mini-Mental States Examination (MMSE) scores to 16 patients with dementia without PTSD. Demographic characteristics, co-morbid diagnoses, global Assessment of Functioning (GAF), Cohen-Mansfield Agitation Inventory (CMAI), and paranoid items of Brief Psychiatric Rating Scale (BPRS) and Positive and Negative Syndrome Scale for Schizophrenia (PANSS) were assessed. The patients with diagnoses of dementia with PTSD did not differ significantly in their clinical presentation, hospital course, and condition at discharge from patients with dementia without PTSD. Chi-square analysis showed that significantly more subjects in the PTSD group were prescribed anti-depressants compared to the non-PTSD group. Interestingly, within the PTSD group, the subgroup of patients who were former prisoners of war had a significantly higher mean score for paranoia and significantly less verbal agitation. This pilot study reveals that a diagnosis of PTSD alone is not sufficient to influence behavior in veterans with dementia; however, we also present provocative results that patients with more severe trauma (POW) do have changes in their behavior.

Head injury as a predictor of psychological outcome in combat veterans

Although it is recognized that psychosocial variables influence the expression of psychopathology following trauma exposure, physiological variables have received less attention as potential mediators of psychological outcome in trauma victims. The purpose of this study was to examine the relationship of head injury to psychological outcome in 171 combat veterans seeking compensation for service-connected disabilities for mental disorders attributed to etiologies other than head injury. Veterans underwent structured psychiatric diagnostic interview and completed self-report measures of combat exposure, posttraumatic stress disorder (PTSD), depression, and occurrence of head injury. Comparisons between veterans with and without history of head injury indicated that head injury was associated with more severe depression. Regression analysis suggested that head injury predicted depression, but not PTSD, severity.