Post-traumatic Stress Disorder - Contemporary Analysis of Medico Legal Evidential Issues

In DSM-5, one of the two main classification schemes of mental disorders (APA, 2013), the diagnosis of Post-Traumatic Stress Disorder (PTSD) has undergone multiple, albeit minor, changes. It now comprises four, not three, symptom clusters with the addition of persistent negative beliefs and distorted negative beliefs about oneself, plus a dissociative specifier (de-personalisation and derealization). Overall prevalence of this diagnosis is unlikely to change, but the greater heterogeneity of individuals being diagnosed with PTSD is probable (Zoellner et al, 2013). This paper summarises and discusses the many important medico-legal issues surrounding the PTSD disorder and its diagnosis and implications for both experts and lawyers. Experts, psychological and psychiatric, working in civil forensic context provide opinion on the presence or absence of psychological injury on the basis of diagnosis, causation and prognosis. The DSM diagnostic criteria for PTSD have been revised repeatedly since the mid-nineteenth century (Thomas, 2013) with PTSD being referred to as “Psychiatry’s problem child” (Gaughwin, 2008). Difficulties have included: ambiguity about traumatic nature of the event; absence of symptom development after traumatic nature of event; confounding prior history of traumatic events, and the coherence of traumatic experiences and their disruptive nature. The application of the concept PTSD has been further complicated by apparent overlap with other conditions in which a wide array of cognitive, behavioural and emotional symptoms are also present; such as Borderline Personality Disorder. The concept of Complex-PTSD appeared in the clinical literature in the early 1990’s (Herman, 1992) and it helpfully made the link between multiple traumatic experiences in childhood and subsequent clinical presenta-tions in adulthood. Importantly, the array of cognitive, behavioural and emotional symptoms often associated with Borderline Personality Disorder and Psychosis, can then, in some cases, be seen as a way of coping with, and as a reaction to, repeated and cumulative traumatic experiences in childhood. Medico-legal implications of these changes and the overall diagnosis itself include the following key areas: Traumatic Stressor definition, differential diagnosis and comorbidity, causation, reliability and validity concerns, the use of legal tests and overall evidential robustness. As with previous versions of DSM, the new DSM-5 has been criticized for both reliability and validity problems, and PTSD is no exception. For trauma survivors, clinical diagnosticians need to carefully assess pre-trauma functioning and consider that another diagnosis besides PTSD may be equally or even better warranted and have more accurate prognostic opinions