Vulnerability To PTSD

PTSD is classified as an anxiety disorder in DSM IV. It occurs following a traumatic event, such as a sexual assault or exposure to a road traffic accident. Direct exposure to the trauma is not essential to the development of the disorder (for example people can develop the disorder  on learning about the death of a loved one).

Whilst PTSD only develops following a traumatic event, for the majority of people who experience a trauma, PTSD does not follow. The National Co morbidity Study (Perkonigg 2000) found that 56% of Americans experience a lifetime trauma yet only 8% develop PTSD. In terms of road traffic accident victims,  Breslau et al’s study (1991) found that of 10% of young adults who had been involved in a serious RTA only 12% of them went on to develop PTSD.

So what makes some people more likely to develop PTSD than others?
The vulnerability of the victim is an important question to answer in the assessment of psychological trauma, particularly for the purpose of medico legal assessment and reporting. It is often a difficult question to answer. Three areas of vulnerability have been discussed in the literature, these are a) pre trauma, b) peri trauma and c) post trauma factors.

a) Pre trauma risk factors
Theseare the factors that have been found to increase risk of development of PTSD that were apparent prior to the index accident. They can be considered “pre disposing” or precipitating factors. Some of the significant factors that have been identified are:

1) Previous psychological disorders
Enquiry needs to be made about previous psychological problems/ disorders. If there is a positive response then information about timescales should be sought. Was there any evidence of psychological difficulties at just prior to the index event (pre existing disorder?) or were the problems some time ago? Medical records can provide a useful means of investigating / corroborating the clients self report.  Both Axis 1 and Axis 2 disorders should be considered. A previous diagnosis of an Axis 2 disorder (Personality Disorder) increases the risk of developing an Axis 1 disorder, such as PTSD, and a previous diagnosis of PTSD increases the vulnerability to further episodes.

2)  History of psychological trauma.
Information about exposure to any previous trauma should be obtained. This includes information about previous road traffic accidents or early trauma, such as childhood abuse or neglect. A history of childhood trauma increases the risk of PTSD. Past trauma can act in a cumulative way and the accident might need to be seen as “the straw that broke the camels back”.

3)Life Stressors
The loss of a job or a relationship breakdown prior to the index event can
increase vulnerability.

4) Family history of psychological problems.
Information about mental health problems in first-degree relatives should be sought. Studies have found that those trauma victims developing PTSD are more likely to have first-degree relatives with mood, anxiety or substance use disorders. (Davidson, 1985).

b) Peri traumatic factors.
These are the “during trauma” vulnerability factors, for instance:

1)  Dissociation.
This is commonly associated with traumatic events and can be viewed as a coping mechanism. However, where a person dissociates during a trauma there is greater risk that they will go on to develop PTSD. People who have experienced previous trauma are more likely to dissociate.

2)  Severity of the trauma
Where the trauma could be considered objectively to be “low level”, yet it results in PTSD symptoms, then personal vulnerability is likely to have a greater weighting. More severe trauma is more likely to result in PTSD (Durand 2006).

c) Post Traumatic factors:
Significant post trauma factors that have been identified are:

1)  Lack of social support.
This been identified as an important factor in recovery after trauma.

2)  Schema change
The person’s view of the world might be radically altered. The accident might challenge their sense of trust or safety.

References
Breslau, N, Davis, G, Andreski, P, Peterson, E, (1991) Traumatic events and PTSD in an urban population of young adults. Achieves of general psychiatry 48, 216-222

Davidson, J, Schwartz, M, Storck, R,  Krishnan, E, Hammett, E. (1985) A diagnositic and family study of PTSD. American Journal of Psychiatry 142, 90-93
Durand V, Barlow, D, (2006) Anxiety Disorders. Taflinger, M. (Ed.), Essentials of Abnormal Psychology  (pp. 155-161). Belmont, CA: Thomas Wadsworth.

Perkonigg, R. C. Kessler, S. Storz, H-U. Wittchen(200) Traumatic events
and post-traumatic stress disorder in the community: prevalence, risk factors and comorbidity,  Acta Psychiatrica Scandinavica, (101) 46–59,