Imagine you are the survivor of a horrible car crash. One day, while you’re walking down the street, you hear a car horn followed by a screeching noise. Before you get a chance to look around and figure out what happened, you feel a sudden rush of adrenaline. Fear paralyzes you from head to toe, and your mind fills up with images of the accident in which you were involved not long ago. It may look like you’re overreacting from the outside, but from the inside, everything feels so ‘real’ and overwhelming. And so, you sit there shaking and waiting for something horrible to happen.

Post-traumatic stress disorder is a common condition that affects millions of people across the world. Up to date recommendations based on the best available evidence are vital to prevent and treat this debilitating condition. In this issue, we are bringing together a series of systematic reviews and meta-analyses that underpinned the development of the 2018 International Society for Traumatic Stress Studies Guidelines.

Background: Treatments for posttraumatic stress (PTS) are effective for many but not all people. There is a continued need to further our understanding of psychological mechanisms involved in the development and maintenance of PTS. Research has examined dysregulation of negative affect (NA) in PTS but relatively little attention has been paid to the role of dysregulation of positive affect (PA) in PTS.

Moral injury is the profound psychological distress which can arise following participating in, or witnessing, events which transgress an individual’s morals and include harming, betraying, or failure to help others, or being subjected to such events, e.g. being betrayed by leaders. It has been primarily researched in the military, but it also found in other professionals such as healthcare workers coping with the COVID-19 pandemic and civilians following a wide range of traumas.