A history of trauma exposure (as defined in Chapter A4) among clients of Australian AOD treatment services is the norm rather than the exception, with more than 80% reporting having experienced a traumatic event in their lifetime [83, 137, 138, 378]. Most clients have experienced multiple traumas, and more than half have experienced trauma during childhood [83, 137, 138, 378]. The types of events experienced are many and varied, but the most commonly reported include having been physically or sexually assaulted, witnessing a serious injury or a death, being threatened with a weapon, or held captive [83, 137, 138]. Given these high rates of trauma it is not surprising that up to two-thirds of Australians entering AOD treatment services also experience PTSD [76]. Regardless of whether a person goes on to develop PTSD or any other mental disorder, traumatic events are often life-changing, and can redefine a person’s views about themselves (e.g., feeling weak, bad, or worthless), the world around them (e.g., the world is not safe), and how they relate to it (e.g., people cannot be trusted). These beliefs may be particularly well-entrenched in those who have experienced childhood trauma [379].
A history of trauma exposure may be integrally linked with the person’s current AOD use. A number of clients who have experienced trauma describe their AOD use as an attempt to self-medicate the thoughts and feelings they have experienced as a consequence of trauma, and there is evidence from a variety of studies to support such a relationship [30]. Although AOD use may provide short-term relief, growing tolerance to the effects of AOD can lead to increased use in an effort to obtain sufficient symptom reduction. In the absence of AOD, PTSD symptoms may worsen, making it difficult for clients to maintain abstinence or reduced use [380]. It should be noted however, that, as with symptoms of depression and anxiety, on average, PTSD symptoms also decline in the context of well managed withdrawal [381–383]. Nonetheless, given the high rates of trauma exposure and PTSD among people with AOD use disorders, and the fundamental role that trauma symptoms may play in a person’s recovery, experts have strongly advocated for trauma-informed care approaches to be adopted in AOD treatment settings [136, 141, 384].