Clinical Study of Biomarkers of Stress Resilience: Role of ELK1 and GPR56

70% of Europeans will be exposed to a potentially traumatic event (PTE). Following this experience, people are likely to develop various psychiatric disorders such as post-traumatic stress disorder (PTSD) or a major depressive episode (MDE). However, not all subjects have the same risk to develop a pathology, and resilience capacities, which depend on multiple factors are difficult to predict. Currently, there are no objective tools to stratify exposed subjects according to their risk of developing pathological responses to stress, which leads to difficulties in allocating means of prevention and treatment. Recently, new biological hypotheses explaining vulnerability/resilience to stress and depression, implicating the GPR56 and ELK1 genes, have been described. Previous studies have shown that evaluation of the vulnerability risk can be obtained from clinical, cognitive, biological or brain imaging variables, but no study has integrated these different approaches. Therefore, the project presented here aims at integrating behavioral, biological and neuroimaging data to predict the development of psychiatric disease. In this study, a prospective cohort of 255 violent trauma victims will be set up in 3 French cities for a period of 2 years. Eligible subjects will be included in the month following PTE and will be followed longitudinally for 12 months. Evaluations at 1, 3, 6 and 12 months will be performed, during which the subject will complete various clinical and cognitive tests. A blood sample will be collected at each visit to study biological processes including the regulation of genetic and epigenetic expression, in particular the expression of the GPR56 and ELK1 genes in the blood. For eligible subjects a brain MRI will be proposed at the first visit. We hypothesize that the genetic expression of ELK1 and GPR56 is predictive of the development of psychiatric pathologies at 6 and 12 months post-PTE. The ambition of this project is also to highlight the importance of a multimodal approach integrating a triad of markers (behavioral, biological and neuroimaging) to test this hypothesis.