RESUMEN
Neural substrates of fatigue in traumatic brain injury (TBI) are not well understood despite the considerable burden of fatigue on return to productivity. Fatigue is associated with diminishing performance under conditions of high cognitive demand, sense of effort, or need for motivation, all of which are associated with cognitive control brain network integrity. We hypothesize that the pathophysiology of TBI results in damage to diffuse cognitive control networks, disrupting coordination of moment-to-moment monitoring, prediction, and regulation of behavior. We investigate the cingulo-opercular (CO) and frontoparietal (FP) networks, which are engaged to sustain attention for task and maintain performance. A total of 61 individuals with mild TBI and 42 orthopedic control subjects participated in functional MRI during performance of a constant effort task requiring altering the amount of effort (25, 50, or 75% of maximum effort) utilized to manually squeeze a pneumostatic bulb across six 30-s trials. Network-based statistics assessed within-network organization and fluctuation with task manipulations by group. Results demonstrate small group differences in network organization, but considerable group differences in the evolution of task-related modulation of connectivity. The mild TBI group demonstrated elevated CO connectivity throughout the task with little variation in effort level or time on task (TOT), while CO connectivity diminished over time in controls. Several interregional CO connections were predictive of fatigue in the TBI group. In contrast, FP connectivity fluctuated with task manipulations and predicted fatigue in the controls, but connectivity fluctuations were delayed in the mild traumatic brain injury (mTBI) group and did not relate to fatigue. Thus, the mTBI group's hyper-connectivity of the CO irrespective of task demands, along with hypo-connectivity and delayed peak connectivity of the FP, may allow for attainment of task goals, but also contributes to fatigue. Findings are discussed in relation to performance monitoring of prediction error that relies on internal cues from sensorimotor feedback during task performance. Delay or inability to detect and respond to prediction errors in TBI, particularly evident in bilateral insula-temporal CO connectivity, corresponds to day-to-day fatigue and fatigue during task performance.
RESUMEN
OBJECTIVE: This study examined the impact of early life trauma (ELT) on cardio-metabolic health in veterans from post-9/11 conflicts who experience significant stress from deployment and reintegration. METHOD: Three hundred thirty-seven veterans from the Translational Research Center for Traumatic Brain Injury and Stress Disorders study underwent physiological assessments, including blood pressure and waist circumference. Fasting blood samples were collected to measure metabolic syndrome (MetS; cholesterol/triglycerides/glucose). ELT history was determined using the Traumatic Life Events Questionnaire. Posttraumatic stress disorder (PTSD) symptoms were assessed using the Clinician-Administered PTSD Scale. Logistic regression models examined the association of ELT and MetS diagnostic criteria while controlling for confounders. RESULTS: The adjusted logistic regression showed a significant relationship between interpersonal ELT (IP ELT) and risk of MetS, with IP ELT having an approximately 3-fold increase in the risk of cardio- metabolic syndrome compared with those with no trauma (odds ratio [OR] = 3.06, p < .05). IP ELT was associated with over a 2-fold increased risk of elevated triglycerides compared with those with no trauma (OR = 2.06, p < .05). PTSD symptoms also explained in part the IP-ELT/MetS relationship. Veterans with any ELT were significantly more likely to meet for a current diagnosis of PTSD. CONCLUSIONS: Our findings suggest that veterans with IP ELT are more likely to meet MetS and PTSD diagnostic criteria than veterans without IP ELT. This is concerning considering the young age of the sample and stresses the importance of an integrated and holistic approach in the assessment of physical and mental health in returning veterans. (PsycINFO Database Record (c) 2019 APA, all rights reserved).