Trauma- and stressor-related disorders (TSRD) is a new category in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013). The specific criterion for inclusion in this diagnostic category is the explicit exposure to a traumatic or stressful event.
Several disorders have been incorporated into the TSRD category as individuals exhibit a wide range of reactions following trauma. The disorders in this new category are reactive attachment disorder, disinhibited social engagement disorder, posttraumatic stress disorder (PTSD), acute stress disorders (ASD), and adjustment disorders. Of these, adjustment disorder, ASD, and PTSD are the most prevalent. In order to qualify for a diagnosis of PTSD, explicit exposure to the most severe stress (PTSD Criterion A) is required, while criteria for diagnosis of an adjustment disorder requires exposure to the least level of stress.
Immediately following exposure to a distressing event, a diagnosis of an adjustment disorder or ASD (providing diagnostic criteria are fulfilled) can be established. However, the criterion for ASD is that a short-term reaction that persists from 3 days to 1 month exists. Should symptoms last longer than a month, a diagnosis of PTSD may apply if specific. For the sake of brevity, this chapter will consider only PTSD and ASD.
The development of PTSD may occur following exposure to a traumatic event where severe threat or injury occurred. However, a straightforward trajectory does not always exist. For instance, while most people with ASD also develop PTSD, many with PTSD do not initially display ASD (Bryant et al., 2008). Many develop PTSD more than 6 months post-trauma, a phenomenon known as delayed onset PTSD. McFarlane (2010) argues that a key reason for this is the escalating process of increasing sensitisation, which progresses an over-reactivity to subtle environmental cues associated with the trauma. PTSD can present at any age; however, there are separate diagnostic criteria for children under the age of 6 (Scheeringa, Zeanah, & Cohen, 2011).
Events that may precipitate PTSD include violent assault, natural disasters, wars, or accidents; for example, direct exposure to natural disasters such as bush fires in Australia (McFarlane, 1990; Parslow, Jorm, & Christensen, 2006) and earthquakes in New Zealand (NZ; Fergusson et al., 2014). Intimate interpersonal violence has the highest reported risk factor for developing PTSD (Forbes et al., 2014). Cumulative stress can also precipitate PTSD.