Faculty Bibliography

Prolonged stress can have long-lasting effects on cognition. Animal models suggest that deficits in executive functioning could result from alterations within the mesofrontal circuit. We investigated this hypothesis in soldiers before and after deployment to Afghanistan and a control group using functional and diffusion tensor imaging. Combat stress reduced midbrain activity and integrity, which was associated to compromised sustained attention. Long-term follow-up showed that the functional and structural changes had normalized within 1.5 y. In contrast, combat stress induced a persistent reduction in functional connectivity between the midbrain and prefrontal cortex. These results demonstrate that combat stress has adverse effects on the human mesofrontal circuit and suggests that these alterations are partially reversible.

BACKGROUND: It has been suggested that pro-inflammatory cytokine signaling to the brain may contribute to severe fatigue. We propose that not only the level of circulating cytokines, but also increased reactivity of target cells to cytokines contributes to the effect of cytokines on behavior. Based on this concept, we assessed the reactivity of peripheral blood cells to IL-1beta in vitro as a novel approach to investigate whether severe fatigue is associated with increased pro-inflammatory signaling. METHODS: We included 504 soldiers before deployment to a combat-zone. We examined fatigue severity and the response to in vitro stimulation with IL-1beta prior to deployment (T0), and 1 (T1) and 6 months (T2) after deployment. IL-8 production was used as read-out. As a control we determined LPS-induced IL-8 production. The presence of severe fatigue was assessed with the Checklist Individual Strength (CIS-20R). Differences in dose-response and the longitudinal course of IL-1beta and LPS-induced IL-8 production and fatigue severity were investigated using repeated measures ANOVA. RESULTS: At T2, the group who had developed severe fatigue (n = 65) had significantly higher IL-1beta-induced IL-8 production than the non-fatigued group (n = 439). This group difference was not present at T0, but developed over time. Longitudinal analysis revealed that in the non-fatigued group, IL-1beta-induced IL-8 production decreased over time, while IL-1beta-induced IL-8 production in the fatigued group had not decreased. To determine whether the observed group difference was specific for IL-1beta reactivity, we also analyzed longitudinal LPS-induced IL-8 production. We did not observe a group difference in LPS-induced IL-8 production. CONCLUSIONS: Collectively, our findings indicate that severe fatigue is associated with a higher reactivity to IL-1beta. We propose that assessment of the reactivity of the immune system to IL-1beta may represent a promising novel method to investigate the association between behavioral abnormalities and pro-inflammatory cytokine signaling.

BACKGROUND: Clinical and neurobiological evidence for a dissociative subtype of posttraumatic stress disorder (PTSD) has recently been documented. A dissociative subtype of PTSD is being considered for inclusion in the forthcoming Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5) to address the symptoms of depersonalization and derealization found among a subset of patients with PTSD. This article reviews research related to the dissociative subtype including antecedent, concurrent, and predictive validators as well as the rationale for recommending the dissociative subtype. METHODS: The relevant literature pertaining to the dissociative subtype of PTSD was reviewed. RESULTS: Latent class analyses point toward a specific subtype of PTSD consisting of symptoms of depersonalization and derealization in both veteran and civilian samples of PTSD. Compared to individuals with PTSD, those with the dissociative subtype of PTSD also exhibit a different pattern of neurobiological response to symptom provocation as well as a differential response to current cognitive behavioral treatment designed for PTSD. CONCLUSIONS: We recommend that consideration be given to adding a dissociative subtype of PTSD in the revision of the DSM. This facilitates more accurate analysis of different phenotypes of PTSD, assist in treatment planning that is informed by considering the degree of patients' dissociativity, will improve treatment outcome, and will lead to much-needed research about the prevalence, symptomatology, neurobiology, and treatment of individuals with the dissociative subtype of PTSD.

BACKGROUND: Biological correlates of posttraumatic stress disorder (PTSD) have mostly been studied using cross-sectional or posttrauma prospective designs. Therefore, it remains largely unknown whether previously observed biological correlates of PTSD precede trauma exposure. We investigated whether glucocorticoid receptor (GR) pathway components assessed in leukocytes before military deployment represent preexisting vulnerability factors for development of PTSD symptoms. METHODS: Four hundred forty-eight male soldiers were assessed before and 6 months after deployment to a combat zone. Participants were assigned to the PTSD or comparison group based on Self-Rating Inventory for PTSD scores after deployment. Logistic regression analysis was applied to predict development of a high level of PTSD symptoms based on predeployment GR number, messenger (m)RNA expression of GR target genes FKBP5, GILZ, and SGK1, plasma cortisol, and childhood trauma. We also investigated whether predeployment GR number and FKBP5 mRNA expression were associated with single nucleotide polymorphisms in the GR and FKBP5 genes, either alone or in interaction with childhood trauma. RESULTS: Several GR pathway components predicted subsequent development of a high level of PTSD symptoms: predeployment high GR number, low FKBP5 mRNA expression, and high GILZ mRNA expression were independently associated with increased risk for a high level of PTSD symptoms. Childhood trauma also independently predicted development of a high level of PTSD symptoms. Additionally, we observed a significant interaction effect of GR haplotype BclI and childhood trauma on GR number. CONCLUSIONS: Collectively, our results indicate that predeployment GR pathway components are vulnerability factors for subsequent development of a high level of PTSD symptoms.

BACKGROUND: PTSD has been associated with altered hypothalamus-pituitary-adrenal-axis (HPA-axis), immune and sympathetic nervous system (SNS) regulation. The purpose of this study was to evaluate the effect of cognitive stress on these systems in PTSD patients and controls. METHODS: The subjective units of distress score (SUDS), NK-cell response, plasma levels of noradrenalin and ACTH in response to cognitive stress were assessed in male veterans with PTSD (n=15) and age, region and year of deployment matched veterans without psychopathology (n=15). RESULTS: The challenge induced an increase in SUDS, noradrenalin, ACTH and NK-cell response in both groups. Baseline levels of ACTH were lower in PTSD patients. The test was experienced as more stressful by PTSD patients and resulted in an augmented ACTH response in patients. The noradrenalin and NK-cell responses showed no group differences. The ACTH response correlated with the severity of symptoms in patients, and the noradrenalin response correlated with the ACTH and NK-cell response in controls, but not in patients. DISCUSSION: PTSD patients experience more distress and present with an exaggerated pituitary response to this stressor. In addition, our results suggest an altered interaction between the HPA-axis, SNS and immune system in PTSD.