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.

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.

Driving simulator performance was examined in Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) Veterans to objectively evaluate driving abilities among this cohort who self-report poorer driving safety postdeployment. OIF/OEF Veterans (n = 25) and age- and education-matched civilian controls (n = 25) participated in a 30 min driving simulator assessment that measured the frequency of minor, moderate, and severe driving errors. Frequency of errors in specific content domains (speed regulation, positioning, and signaling) was also calculated. All participants answered questions about number of lifetime traffic "warnings," moving violation tickets, and accidents. Veterans completed the Posttraumatic Stress Disorder (PTSD) Checklist-Military Version. On the driving simulator assessment, Veterans committed more minor, moderate, severe, and speeding errors and reported poorer lifetime driving records than the civilian control group. Exploratory analyses revealed an association between increasing errors on the driving simulator with increasing symptoms of PTSD, although statistically this correlation did not reach significance. These findings suggest that Veterans perform more poorly on an objective evaluation of driving safety and that the presence of PTSD could be associated with worse performance on this standardized driving simulator assessment.

Research has shown that attention can be abnormally drawn to salient threat- or trauma-related information in individuals with posttraumatic stress and related psychological symptoms. The nature of this attentional bias is thought to derive from capture of attention toward potential threat overpowering the volitional, goal-directed attentional system. However, it is unclear whether this pattern of attentional dysregulation generalizes to salient, but non-emotional types of information. Using a well-established and sensitive measure of attentional capture, the current study demonstrates that posttraumatic psychological symptom severity is associated with the capture of attention by visually salient, non-emotional distractors. Specifically, during visual search for a unique shape, the presence of a task-irrelevant but salient color singleton disrupted search efficiency, and this disruption was correlated with both posttraumatic stress disorder (PTSD) and depression symptom severity as assessed by self-report. These findings suggest that posttraumatic stress and depression may be characterized as involving a general alteration of the balance between salience-based and goal-directed attentional systems.

Posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) in military personnel is increasing dramatically following the OEF/OIF conflicts and is associated with alterations to brain structure. The present study examined the relationship between PTSD and cortical thickness, and its possible modification by mTBI, in a 104-subject OEF/OIF veteran cohort ranging in age from 20 to 62 years. For each participant, two T1-weighted scans were averaged to create high-resolution images for calculation of regional cortical thickness. PTSD symptoms were assessed using the Clinician Administered PTSD Scale (CAPS) and scores were derived based on the previous month's symptoms ("current") and a Cumulative Lifetime Burden of PTSD (CLB-P) reflecting the integral of CAPS scores across the lifetime. Mild TBI was diagnosed using the Boston Assessment of TBI-Lifetime (BAT-L). Results demonstrated a clear negative relationship between current PTSD severity and thickness in both postcentral gyri and middle temporal gyri. This relationship was stronger and more extensive when considering lifetime burden (CLB-P), demonstrating the importance of looking at trauma in the context of an individual's lifetime, rather than only at their current symptoms. Finally, interactions with current PTSD only and comorbid current PTSD and mTBI were found in several regions, implying an additive effect of lifetime PTSD and mTBI on cortical thickness.

BACKGROUND: Chronic misuse of alcohol results in widespread damage to the brain. Prior morphometric studies have examined cortical atrophy in individuals with alcoholism; however, no previous studies have examined alcohol-associated atrophy using cortical thickness measurements to obtain regional mapping of tissue loss across the full cortical surface. METHODS: We compared cortical thickness measures from 31 abstinent individuals with a history of prior alcohol abuse to 34 healthy nonalcoholic control participants (total sample size = 65). Cortical surface models were created from high-resolution T1-weighted images, and cortical thickness was then estimated as the distance between the gray matter/white matter boundary and the outer cortical surface. RESULTS: Abstinent alcoholics showed reduced whole-brain thickness as compared to nonalcoholic participants. Decreases in thickness were found bilaterally in (i) superior frontal, (ii) precentral, (iii) postcentral, (iv) middle frontal, (v) middle/superior temporal, (vi) middle temporal, and (vii) lateral occipital cortical regions. Decreased cortical thickness in the alcoholic group was associated with severity of alcohol abuse. CONCLUSIONS: These findings demonstrate widespread reduction in cortical thickness as a consequence of chronic alcoholism, with most severe reductions in frontal and temporal brain regions.