Sex and Gender in Psychotrauma Research

BackgroundPosttraumatic stress disorder (PTSD) is two to three times more common in women than in men. To better understand this phenomenon, we need to know why men, women, and possibly individuals with other sex/gender identities respond differently to trauma. To stimulate sex and gender sensitive research, the European Journal of Psychotraumatology (EJPT) was the first journal to adopt a gender policy. In addition, a call for papers entitled Integrating and Evaluating Sex and Gender in Psychotrauma Research was announced. ObjectiveThis special issue synthesizes the past five years of psychotrauma research with regard to sex/gender differences. MethodSeventy-seven articles were identified from EJPT archives, including five systematic reviews. These articles examined sex differences and/or gender differences in exposure to trauma, posttraumatic stress responses, or how sex and gender impacts (mental) health outcomes or treatment responses. ResultsFindings from these studies outlined that: 1. sex and gender still need to be more clearly defined, also in relation to the context that codetermine trauma responses, like other ‘diversity’ variables; 2. in most studies, sex and gender are measured or reported as binary variables; 3. sex and gender are important variables when examining trauma exposure, responses to these events, symptoms trajectories, and mental and physical health outcomes across the life span; and 4. in PTSD treatment studies, including a meta-analysis and a systematic review, sex and gender were not significant predictors of treatment outcome.ConclusionFuture research must focus on sex and gender as important and distinct variables; they should include sex and gender in their statistical analyses plan to better clarify associations between these variables and (responses to) psychotrauma. To enhance reporting of comparable data across studies, we provide suggestions for future research, including how to assess sex and gender.</p

Impact of herbivores on nitrogen cycling:contrasting effects of small and large species

Herbivores are reported to slow down as well as enhance nutrient cycling in grasslands. These conflicting results may be explained by differences in herbivore type. In this study we focus on herbivore body size as a factor that causes differences in herbivore effects on N cycling. We used an exclosure set-up in a floodplain grassland grazed by cattle, rabbits and common voles, where we subsequently excluded cattle and rabbits. Exclusion of cattle lead to an increase in vole numbers and a 1.5-fold increase in net annual N mineralization at similar herbivore densities (corrected to metabolic weight). Timing and height of the mineralization peak in spring was the same in all treatments, but mineralization in the vole-grazed treatment showed a peak in autumn, when mineralization had already declined under cattle grazing. This mineralization peak in autumn coincides with a peak in vole density and high levels of N input through vole faeces at a fine-scale distribution, whereas under cattle grazing only a few patches receive all N and most experience net nutrient removal. The other parameters that we measured, which include potential N mineralization rates measured under standardized laboratory conditions and soil parameters, plant biomass and plant nutrient content measured in the field, were the same for all three grazing treatments and could therefore not cause the observed difference. When cows were excluded, more litter accumulated in the vegetation. The formation of this litter layer may have added to the higher mineralization rates under vole grazing, through enhanced nutrient return through litter or through modification of microclimate. We conclude that different-sized herbivores have different effects on N cycling within the same habitat. Exclusion of large herbivores resulted in increased N annual mineralization under small herbivore grazin

The role of acute cortisol and DHEAS in predicting acute and chronic PTSD symptoms

Background: Decreased activation of the hypothalamus-pituitary-adrenal (HPA) axis in response to stress is suspected to be a vulnerability factor for posttraumatic stress disorder (PTSD). Previous studies showed inconsistent findings regarding the role of cortisol in predicting PTSD. In addition, no prospective studies have examined the role of dehydroepiandrosterone (DHEA), or its sulfate form DHEAS, and the cortisol-to-DHEA(S) ratio in predicting PTSD. In this study, we tested whether acute plasma cortisol, DHEAS and the cortisol-to-DHEAS ratio predicted PTSD symptoms at 6 weeks and 6 months post-trauma. Methods: Blood samples of 397 adult level-1 trauma center patients, taken at the trauma resuscitation room within hours after the injury, were analyzed for cortisol and DHEAS levels. PTSD symptoms were assessed at 6 weeks and 6 months post-trauma with the Clinician Administered PTSD Scale. Results: Multivariate linear regression analyses showed that lower cortisol predicted PTSD symptoms at both 6 weeks and 6 months, controlling for age, gender, time of blood sampling, injury, trauma history, and admission to intensive care. Higher DHEAS and a smaller cortisol-to-DHEAS ratio predicted PTSD symptoms at 6 weeks, but not after controlling for the same variables, and not at 6 months. Conclusions: Our study provides important new evidence on the crucial role of the HPA-axis in response to trauma by showing that acute cortisol and DHEAS levels predict PTSD symptoms in survivors of recent trauma. © 2014 Elsevier Ltd