Post Traumatic Stress Disorder (PTSD)

Definition and defining characteristics of PTSD

Posttraumatic Stress Disorder, or PTSD as it is commonly referred to, is the development of a set of symptoms including intense anxiety that occurs following exposure to extreme trauma that is severe enough to have actually caused serious injury or threatened to cause injury or death.

The anxiety response is severe, horrific, and may involve feelings of helplessness. The trauma is of sufficient magnitude that most people would judge it to be traumatic e.g. being caught in a tsunami or an earthquake.

The characteristic symptoms of posttraumatic stress disorder are summarized here, but a more complete description is provided in the Appendix.

The symptoms can be divided into three main categories: re-experiencing the trauma; avoidance and numbing; and increased psychological and physiological arousal.

Hence the person with posttraumatic stress disorder experiences intrusive memories, images, or thoughts of the trauma. Also they may avoid anything that they associate with the original disaster e.g. beaches if that is where they were when the tsunami occurred.

Emotionally, the person with posttraumatic stress disorder may become numb to situations which normally would produce an emotional response e.g. getting an affectionate hug from their mate.

Hypervigilance is another cardinal feature of this condition; this means the person is much more focussed on possible dangers in the environment than is normal e.g. taking extremely caution in crossing a street e.g. looking out for approaching cars if they have been in a car accident.

A somewhat puzzling feature of posttraumatic stress disorder is that although it usually occurs within several months of the trauma, it can also manifest itself much later e.g. Vietnam war veterans can exhibit the symptoms decades later.

Lifetime prevalence of PTSD

A large epidemiological US survey in 2005 found the lifetime prevalence for posttraumatic stress disorder to be 6.8%, making it the third most common anxiety disorder surpassed only by specific phobia and social phobia (Kessler et al 2005).

A more recent epidemiological study of 34,653 persons in the US found an almost identical lifetime prevalence of 6.4% (Pietrzak et al 2011).

The most common trauma were the “unexpected death of someone close, serious illness or injury to someone close, and sexual assault. The lifetime prevalence was greater in women (8.6%) than in men (4.1%) perhaps reflecting the greater likelihood of sexual and or physical aggression against women.

There are a couple of extremely important issues arising out of how one defines posttraumatic stress disorder. The first issue involves the fact that quite generally psychiatric disorders exist on a continuum of severity and that the exact threshold for inclusion is somewhat arbitrary.

Pietrzak et al (2011) assessed the prevalence of cases where the diagnosis was only partially fulfilled in addition to cases meeting the full criteria for inclusion. They found that the combined lifetime prevalence rate was 13% almost double the figure attained using the more strict criteria.

Thus, this study suggests that the actual number of people needing at least some professional assistance is much larger than thought previously.

The second issue, of at least equal importance to the first, is that recently there has been a move towards codifying a new disorder called “Complex PTSD”. In complex PTSD one extends the focus to childhood traumatization and includes a more general definition of what constitutes a trauma than that given in the DSM-IV.

Another name for complex posttraumatic stress disorder is codependence which of course has received considerable attention for decades from a minority of mental health workers such as Pia Mellody and John Bradshaw.

Treatments for Post Traumatic Stress Disorder

Persons suffering from posttraumatic stress disorder generally have one or more other psychiatric problems (co-morbidities) including depression, anxiety, suicide attempts, and especially substance use disorders e.g. alcohol dependence or abuse.

The latter especially interferes with therapy and must be managed or eliminated before therapy can be effective. The high comorbidity in posttraumatic stress disorder not only increases the need for treatment but makes treatment more complex and demanding of the therapist.

Fortunately, there are a variety of treatment approaches for PTSD but their effectiveness varies considerably. Treatment approaches can be divided into two types; those that focus on the memories associated with the traumatic event and the personal meanings of the trauma for the victim, and those which are more general with a broader focus.

The former treatment approaches are called trauma-focused treatments and include trauma-focused cognitive behaviour therapy and Eye Movement Desensitization and Reprocessing (EMDR) therapy.

The non-trauma focused treatments include various stress management programs, supportive therapy, hypnotherapy, psychodynamic therapy, and interpersonal therapy.

Although there has been some controversy about what treatment approach or approaches are best (see Ehlers et al 2009), recent meta-analysis of extant research indicates that trauma-focused treatments are generally more effective than the more general, non-trauma focused, treatment approaches.

Consequently there is a consensus that trauma-focused psychological treatments are the best first-line treatments for PTSD (Cloitre, 2009; Stein et al 2009), although this may be supplemented in particular cases with more general types of interventions.


Specific diagnostic criteria for posttraumatic stress disorder are provided in the Diagnostic and Statistical Manual , 4th Edition (1994, DSM-IV) of the American Psychiatric Society. The DSM-IV criteria include the following:

  • Exposure to our traumatic event which involved either an actual death or serious injury to the self or others and the person responded with intense fear helplessness or horror.
  • Persistent re-experiencing of the in one or more of the following ways:
    • intrusive memories of the event
    • distressing dreams
    • acting or feeling as if the traumatic event were recurring
    • psychological distress when exposed to cues that are linked to the original trauma
    • physiological signs of an anxiety response when exposed to anything linked to the original trauma
  • Persistent avoidance of stimuli associated with the original trauma and numbing of general responding to. As indicated by three or more of the following:
    • tempting to avoid thoughts feelings or conversation about the trauma
    • attempts to avoid activities places or people that trigger memories of the trauma
    • inability to recall some important aspect of the trauma
    • decreased interest or participation in significant activities
    • detachment from others
    • a narrowing range of affection. E.g. unable to experience affection for others
    • feeling pessimistic about the future. E.g. no expectation to have a normal career marriage or family
  • Persistent symptoms of increased arousal as indicated by two or more of the following:
    • sleep problems
    • irritability
    • difficulty concentrating
    • hypervigilance
    • exaggerated startle response
  • These symptoms must persist for at least 1 month
  • There must be a significant detrimental effect on usual functioning example work, social or interpersonal relationships.

Some modification has been proposed in the existing DSM-IV criteria that assumes three symptom clusters define posttraumatic stress disorder:

  1. Re-experiencing the trauma
  2. Avoidance and numbing
  3. Increased psychological and physiological arousal.

There is substantial research evidence to split the second factor, avoidance and numbing, into two separate factors. The first reason is the clinical evidence that avoidance and numbing express themselves differently in terms of psychopathology and treatment (Asmundson, Stapleton, & Taylor, 2004). The second reason being indications of an improvement in the predictive power of the DSM-IV model if avoidance and numbing are indeed split into separate factors (reviewed in Elhai & Palmieri, 2011).


American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders. (4th ed., text rev.) Washington, DC: Author.

Asmundson, G. J. G., Stapleton, J. A., & Taylor, S. (2004). Are avoidance and numbing distinct PTSD symptom clusters? Journal of Traumatic Stress, 17(6), 467-475.

Cloitre, M. (2009). Effective psychotherapies for posttraumatic stress disorder: A review and critique. CNS Spectrums, 14 (Suppl 1) (2009), pp. 32–43.

Elhai, J. D., & Palmieri, P. A. (2011). The factor structure of posttraumatic stress disorder: A literature update, critique of methodology, and agenda for future research. Journal of Anxiety Disorders, 25(6), 849-854.

Keane, T. M., Marshall, A. D., & Taft, C. T. (2006). Posttraumatic stress disorder: Etiology, Epidemiology, and Treatment Outcome. Annual Review of Clinical Psychology, 2, 161-197.

Kessler, Ronald C., Berglund, Patricia, Demler, Olga, Jin, Robert, Merikangas, K. R., Walters, Ellen E., (2005). Lifetime Prevalence and Age-of-Onset Distributions of DSM-IV Disorders in the National Comorbidity Survey Replication. Archives of General Psychiatry, Vol. 62(6), 593-602.

Pietrzak, R. H., Goldstein, R. B., Southwick, S. M., & Grant, B. F. (2011). Prevalence and Axis I comorbidity of full and partial posttraumatic stress disorder in the United States: Results from Wave 2 of the National Epidemiologic Survey on Alcohol and Related Conditions. Journal of Anxiety Disorders, 25(3), 456-465.

Stein, D.J., Cloitre, M., Nemeroff, C.B., Nutt, D.J. Seedat, S. Shalev A.Y. et al. Cape Town consensus on posttraumatic stress disorder. CNS Spectrums, 14 (Suppl 1) (2009), pp. 52–58

Mental Health News