Exposure to trauma is one of the most important and prevalent risk factors for mental and physical ill-health. Excessive or prolonged stress exposure increases the risk of a wide variety of mental and physical symptoms. However, people differ strikingly in their susceptibility to develop signs and symptoms of mental illness after traumatic stress. Post-traumatic stress disorder (PTSD) is a debilitating disorder affecting approximately 8% of the world’s population during their lifetime, and typically develops after exposure to a traumatic event. Despite that exposure to potentially traumatizing events occurs in a large proportion of the general population, about 80–90% of trauma-exposed individuals do not develop PTSD, suggesting an inter-individual difference in vulnerability to PTSD. While the biological mechanisms underlying this differential susceptibility are unknown, epigenetic changes have been proposed to underlie the relationship between exposure to traumatic stress and the susceptibility to develop PTSD. Epigenetic mechanisms refer to environmentally sensitive modifications to DNA and RNA molecules that regulate gene transcription without altering the genetic sequence itself. In this review, we provide an overview of various molecular biological, biochemical and physiological alterations in PTSD, focusing on changes at the genomic and epigenomic level. Finally, we will discuss how current knowledge may aid us in early detection and improved management of PTSD patients.

Disruption of persistent, stress-associated memories is relevant for treating posttraumatic stress disorder (PTSD) and related syndromes, which develop in a subset of individuals following a traumatic event. Using a stress-enhanced fear learning protocol that results in differential susceptibility in inbred mice, we integrated small-RNA sequencing with quantitative proteomics on basolateral amygdala tissue collected one month after training. We identified persistently changed microRNAs, including mir-135b-5p, and predicted target proteins associated with PTSD-like heightened fear expression. Functional manipulations of mir-135b-5p bidirectionally modulated stress-associated memory. mir-135b-5p is expressed in human amygdala and its passenger strand was elevated in serum from a well-characterized military PTSD cohort. miR-135b-5p is a therapeutic target for dampening persistent, stress-enhanced memory and its passenger strand a potential biomarker for responsivity to a mir-135-based therapeutic. One Sentence Summary: mir-135 can be manipulated to weaken persistent, stress-associated memory and serve as a biomarker of PTSD.

It is a great tribute to Dr Matt Friedman that Psychiatry is republishing two of the foundational papers of the National PTSD Brain Bank. The initiative for the Brain Bank is a long-term investment...