Individuals who develop PTSD represent only a subset of those exposed to trauma, suggesting that certain people are at risk for development of the disorder after exposure to trauma whereas others appear to be more resilient.{dagger} Box 2Go shows some of the established risk factors for PTSD (McFarlane, 1996). The magnitude and degree of exposure to the stressor influence the risk of developing PTSD. Gender also appears to be significant, with twice the rates of PTSD in women than in men, despite lower reported exposure. Previous personality traits, coping styles and experiences also influence the development of PTSD. Repressive coping style, indicated by low anxiety and high defensiveness, appears to reduce the likelihood of developing PTSD (Ginzburg et al, 2002). Other risk factors include previous traumatisation (Smith et al, 1990), peri-traumatic dissociative experiences (Birmes et al, 2003) and early sensitisation of the hypothalamic–pituitary–adrenal (HPA) axis (Yehuda, 1999, 2002).
In some people PTSD has an unremitting course: more than one-third have a clinical diagnosis of the disorder many years after the onset of their index episode (Kessler et al, 1995). The majority of patients who do recover from PTSD still report sub-threshold symptoms (Ehlers et al, 1998).
Anumber of factors have been identified as important in the maintenance of PTSD, including social support and organisational environment. In addition, being divorced and/or widowed, lower education and lower income, concurrent family stressors and a low level of psychosocial functioning appear to be important in the maintenance of chronic PTSD (Zlotnick et al, 2004).
The development of PTSD is therefore the complex result of the interaction of individual vulnerability and resilience with factors related to the severity of trauma. A fictitious clinical example makes the point. Five men were involved in an aeroplane crash. Superficially, all were exposed to severe life-threatening trauma, involving grotesque imagery (a fellow passenger was decapitated and his mutilated remains spread over the crash site). On the basis of the nature of the trauma alone, one might expect all the survivors to develop PTSD.
Box 2 Risk factors for PTSD
Aspect of trauma
* Duration and magnitude of exposure to stressor
* Stressors are sudden and/or occur with no warning
* There is multiple loss of life, mutilation or grotesque imagery
* Criminal violence, especially sexual
Experience during trauma
* Perceived own life to be at real risk
* Perceived lack of control of events, intense fear and helplessness
* Perception of grotesque imagery, especially of human remains or children
* Witnessing or carrying out atrocities, e.g. murder, torture
* High levels of dissociative symptoms at the time of the event
Characteristics of the individual
* Previous psychiatric illness or neuroticism
* Previous exposure to trauma, especially childhood trauma
* Previous coping style
* Denial of trauma and/or avoidance
* Female gender
* Previous acute stress reaction
Post-trauma
* Denial of trauma by others or dismissal of experience
* Lack of social support
However, 18 months later, only two of the five had failed to make a reasonable recovery after a normal stress response. Only one man developed PTSD. His subjective experience of the trauma was particularly unpleasant. There was also evidence that his personality put him at risk. The other man who failed to recover did not have PTSD but was chronically anxious in a way that severely affected his work performance.
Each man’s subjective account of the crash was different, making the point that subjective experience interacts with objective severity to influence the development of psychopathology. It is therefore not possible to state that only extremes of trauma or individual psychological vulnerability lead to the development of PTSD. The relative contributions of past experience and experience of the traumatic event need to be considered during assessment, and have implications for choice of treatment.
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Gwen Adshead and Scott Ferris
Gwen Adshead is Consultant Forensic Psychotherapist at Broadmoor Hospital (Dadd Centre, Crowthorne, Berkshire RG45 7EG, UK. Email: gwen.adshead@wlmht.nhs.uk). Her research interests include psychiatric ethics, moral reasoning in psychiatry and attachment histories in abusive parents. Scott Ferris is Specialist Registrar in Psychotherapy at Forest House, Walthamstow, London and was previously Specialist Registrar in Forensic Psychiatry working in the trauma service at St George’s Hospital, London. His other research interests include attachment and offence representations.
