Examining the effects of chronic pain on work performance in the military.

BACKGROUND: Effectively managing pain is a unique challenge for the U.S. military. Chronic pain has a tremendous detrimental impact on mission readiness throughout the Armed Forces. Examining the effects of chronic pain on readiness is critical to understanding and addressing these challenges. PURPOSE: The purpose of this study was to examine the associations of chronic pain and sleep disruption in the context of work performance among active duty military service members. METHODOLOGICAL ORIENTATION: The study design was a cross-sectional observational study that examined associations between patients with chronic pain and sleep disruption, in the context of work performance. RESULTS: One hundred forty-five participants completed the study. Age, depression, sleep, and pain severity were consistently strong predictors of work performance. CONCLUSIONS: Patients performed better with age, whereas those with depression, sleep disruption, and increased pain severity performed poorly. IMPLICATIONS FOR PRACTICE: Research focused on the differences in work performance among age groups may provide a better understanding of coping strategies. Focused depression research can lead to a greater understanding of how mental health affects pain, sleep, and work. The findings of this study open the door to explore multiple approaches that could lead to treatments and preventions for military members living with chronic pain.

PTSD, but not history of mTBI, is associated with altered myelin in combat-exposed Iraq and Afghanistan Veterans.

OBJECTIVE: To investigate the biological, cognitive, and psychological presentations of combat-exposed Veterans with a history of mild traumatic brain injury (mTBI) and/or posttraumatic stress disorder (PTSD) using a novel white matter imaging technique and comprehensive neuropsychological assessment. METHOD: 74 Iraq and Afghanistan Veterans (mean age 33.89, 90.5% male) with history of mTBI (average 7.25 years since injury), PTSD, both, or neither underwent magnetic resonance imaging (MRI) exams including acquisition of a novel imaging technique, multicomponent-driven equilibrium single-pulse observation of T1/T2 (mcDESPOT) to quantify myelin water fraction (MWF), a surrogate measure of myelin content. Participants also underwent comprehensive neuropsychological assessment and three cognitive composite scores (memory, working memory/processing speed, and executive functioning) were created. RESULTS: There were no significant group differences on the neuropsychological composite scores. ANCOVAs revealed a main effect of PTSD across all a priori regions of interest (ROI) in which PTSD was associated with higher MWF. There was no main effect of mTBI history or TBI by PTSD interaction on any ROI. Significant positive associations were observed between myelin and PTSD symptoms, but no significant associations were found between myelin and neurobehavioral symptoms. No significant associations were found between myelin in the a priori ROIs and the cognitive composite scores. CONCLUSION: This study did not find neuropsychological or MWF differences in combat Veterans with a remote history of mTBI but did find myelin alterations related to PTSD. Psychological trauma should be a primary target for intervention in Veterans with comorbid PTSD and mTBI reporting subjective complaints, given its salience.

Evaluation of objective and subjective clinical outcomes in combat veterans with and without mild TBI and PTSD: A four-group design.

Introduction: Mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) are highly prevalent comorbid conditions in military Veterans. However, lack of appropriate comparison groups has clouded interpretation of the chronic effects of these conditions. The present study evaluated the neuropsychological, psychiatric/neurobehavioral, and functional outcomes associated with mTBI and PTSD in a well-characterized sample of combat-exposed Veterans. Method: Participants included 73 Iraq/Afghanistan Veterans (91.8% male; age: M = 34.00, SD = 6.39) divided into four groups: mTBI-only (n = 23), PTSD-only (n = 14), comorbid mTBI + PTSD (n = 19), and combat-control (CC; n = 17). Participants were administered a neuropsychological assessment and completed questionnaires assessing psychiatric/neurobehavioral symptoms and functional outcomes. Results: Kruskal-Wallis H-tests showed no group differences across measures of neuropsychological functioning; however, there were significant differences across groups on all psychiatric/neurobehavioral variables examined. In general, the comorbid and PTSD-only groups endorsed the most severe symptoms, followed by the mTBI-only and CC groups, respectively. As for functional outcomes, the comorbid and PTSD-only groups had higher rates of service-connection disability and greater perceived decline in work and education-related abilities, relative to the mTBI-only and CC groups, despite similar proportions of Veterans employed or in school in each group. Conclusions: Findings suggest that Veterans with comorbid mTBI + PTSD and PTSD alone are at greatest risk for experiencing long-lasting subjective distress, including negative perceptions of their ability to work or pursue an education, despite being comparable to mTBI-only and CC Veterans on objective measures of functioning. Our results highlight the importance of emphasizing mental health treatment in this population.

The Role of Pain Catastrophizing in Cognitive Functioning Among Veterans With a History of Mild Traumatic Brain Injury.

OBJECTIVE: To determine the role of pain catastrophizing (PC) in neuropsychological functioning in veterans with a history of mild traumatic brain injury (TBI). PARTICIPANTS: Thirty-nine Iraq and Afghanistan combat veterans evaluated in the post-acute phase following mild TBI. METHODS: Participants underwent psychiatric and TBI clinical interviews, neuropsychological tests, and self-report assessments of PC, pain intensity, depression, and posttraumatic stress disorder symptoms. Cognitive functioning composite scores of executive functioning, processing speed, and learning and memory were created. Composites were entered as dependent variables into separate linear regressions to examine relations with PC. RESULTS: Greater PC was associated with worse executive functioning and processing speed even when controlling for confounding variables. CONCLUSIONS: One's interpretation of pain, in addition to pain intensity, has implications for cognitive functioning. Future research is encouraged to determine whether adaptive pain coping mechanisms improve cognitive functioning or, alternatively, whether cognitive rehabilitation strategies reduce PC.

Spatial memory ability during middle age may depend on level of spatial similarity.

Spatial memory impairment is well documented in old age; however, less is known about spatial memory during middle age. We examined the performance of healthy young, middle-aged, and older adults on a spatial memory task with varying levels of spatial similarity (distance). On low similarity trials, young adults significantly outperformed middle-aged adults, who significantly outperformed older adults (Ps < 0.05). On high similarity trials, young adults significantly outperformed middle-aged and older adults (Ps < 0.05); however, middle-aged and older adults did not differ. Subtle age-related changes in spatial memory may emerge during middle age, particularly when spatial similarity is high.

Pilot investigation of a novel white matter imaging technique in Veterans with and without history of mild traumatic brain injury.

OBJECTIVE: The objective of this study is to assess utility of in vivo myelin imaging in combat Veterans with and without history of mild traumatic brain injury (mTBI). We hypothesized that those with history of mTBI would have lower myelin water fraction (MWF), a marker of myelin integrity and content, than those without, and lower MWF would be associated with worse speeded attention/processing speed. RESEARCH DESIGN: Combat Veterans (N = 70) with (n = 42) and without history of mTBI (n = 28) underwent neuroimaging including a novel myelin-sensitive magnetic resonance imaging technique (multicomponent-driven equilibrium single-pulse observation of T1/T2; mcDESPOT) and comprehensive neuropsychological assessment. RESULTS: There were no group differences in MWF using a region-of-interest approach. An exploratory analysis applying limited spatial constraints, however, revealed significantly more 'potholes' (clusters of low MWF) in Veterans with history of mTBI compared to those without. Lower MWF across several ROIs was associated with worse performance on a speeded attention task across groups. CONCLUSION: Veterans in the post-acute period following mTBI showed limited and spatially heterogeneous MWF changes and myelin integrity was significantly related to processing speed. This preliminary evidence for usefulness of mcDESPOT in combat Veterans with history of mTBI warrants future research to determine mcDESPOT's relative utility compared to techniques such as diffusion tensor imaging.

Impaired spatial pattern separation performance in temporal lobe epilepsy is associated with visuospatial memory deficits and hippocampal volume loss.

Individuals with chronic temporal lobe epilepsy (TLE) experience episodic memory deficits that may be progressive in nature. These memory decrements have been shown to increase with the extent of hippocampal damage, a hallmark feature of TLE. Pattern separation, a neural computational mechanism thought to play a role in episodic memory formation, has been shown to be negatively affected by aging and in individuals with known hippocampal dysfunction. Despite the link between poor pattern separation performance and episodic memory deficits, behavioral pattern separation has not been examined in patients with TLE. We examined pattern separation performance in a group of 22 patients with medically-refractory TLE and 20 healthy adults, using a task hypothesized to measure spatial pattern separation with graded levels of spatial interference. We found that individuals with TLE showed less efficient spatial pattern separation performance relative to healthy adults. Poorer spatial pattern separation performance in TLE was associated with poorer visuospatial memory, but only under high interference conditions. In addition, left hippocampal atrophy was associated with poor performance in the high interference condition in TLE. These data suggest that episodic memory impairments in patients with chronic, refractory TLE may be partially due to less efficient pattern separation, which likely reflects their underlying hippocampal dysfunction.

The effect of interference on temporal order memory in individuals with Parkinson's disease.

Memory for the temporal order of items or events in a sequence has been shown to be impaired in older adults and individuals with Parkinson's disease (PD). The present study examined the effects of high and low interference on temporal order memory in individuals diagnosed with PD (n=20) and demographically similar healthy older adults (n=20) utilizing a computerized task used in previously published studies. During the sample phase of each trial, a series of eight circles were randomly presented one at a time in eight different spatial locations. Participants were instructed to remember the sequence in which the circles appeared in the locations. During the choice phase, participants were presented with two circles in two different locations and were asked to indicate which circle appeared earliest in the sample phase sequence. The two circles were separated by one of four possible temporal separation lags (0, 2, 4, and 6), defined as the number of circles occurring in the sample phase sequence between the two choice phase circles. Shorter temporal lags (e.g., 0 and 2 lags) were hypothesized to result in higher interference compared to longer temporal lags (e.g., 4 and 6 lags). The results demonstrated that on trials involving high interference, no differences were found between the two groups. However, healthy older adults significantly outperformed individuals with PD (p<0.05) on trials involving low interference. Although differences were found between the PD and healthy older adult groups, both groups significantly improved on low interference trials compared to high interference trials (p<0.001). The findings indicate that temporal order memory improves in healthy older adults and individuals with PD when interference is reduced. However, individuals with PD demonstrated poorer temporal order memory even with less interference. Therefore, temporal order memory is differentially affected by interference in healthy older adults and individuals with PD. Given that both groups did improve with lessened interference, behavioral interventions that minimize temporal interference potentially could improve memory function in older adults and to a lesser extent in individuals with PD.