Brief presentations of information on aspects of PTSD:

  • Warning Signs
    Warning signs of trauma-related stress
    , from Los Angeles County Department of Mental Health.

  • Warning Signs from APA
    Warning signs of trauma-related stress, from the American Psychological Assn.
  • Normalizing Emotions
    You are not alone! description of normal emotions following a disaster, from the American Red Cross.

The Peniston Protocol
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Research and Education on Post-Traumatic Stress Disorder

Post-Traumatic Stress Disorder: An Overview

by Matthew J. Friedman, M.D., Ph.D.,
Executive Director, National Center for PTSD
Professor of Psychiatry and Pharmacology, Dartmouth Medical School

The risk of exposure to trauma has been a part of the human condition since we have evolved as a species. Attacks by saber tooth tigers or twentieth century terrorists have probably produced similar psychological sequelae in the survivors of such violence. Shakespeare's Henry IV appears to have met many, if not all, of the diagnostic criteria for post-traumatic stress disorder (PTSD), as have other heroes and heroines throughout the world's literature. The history of the development of the PTSD concept is described by Trimble (1985).

In 1980, the American Psychiatric Association added PTSD to the third edition of its Diagnostic and Statistical Manual of Mental Disorders (DSM-III) nosologic classification scheme. Although a controversial diagnosis when first introduced, PTSD has filled an important gap in psychiatric theory and practice. From an historical perspective, the significant change ushered in by the PTSD concept was the stipulation that the etiological agent was outside the individual him or herself (i.e., the traumatic event) rather than an inherent individual weakness (i.e., a traumatic neurosis). The key to understanding the scientific basis and clinical expression of PTSD is the concept of "trauma."

In its initial DSM-III formulation, a traumatic event was conceptualized as a catastrophic stressor that was outside the range of usual human experience. The framers of the original PTSD diagnosis had in mind events such as war, torture, rape, the Nazi Holocaust, the atomic bombings of Hiroshima and Nagasaki, natural disasters (such as earthquakes, hurricanes, and volcano eruptions) and human-made disasters (such as factory explosions, airplane crashes, and automobile accidents). They considered traumatic events as clearly different from the very painful stressors that constitute the normal vicissitudes of life such as divorce, failure, rejection, serious illness, financial reverses and the like. (By this logic adverse psychological responses to such "ordinary stressors" would, in DSM-III terms, be characterized as Adjustment Disorders rather than PTSD.) This dichotomization between traumatic and other stressors was based on the assumption that although most individuals have the ability to cope with ordinary stress, their adaptive capacities are likely to be overwhelmed when confronted by a traumatic stressor.

PTSD is unique among other psychiatric diagnoses because of the great importance placed upon the etiological agent, the traumatic stressor. In fact, one cannot make a PTSD diagnosis unless the patient has actually met the "stressor criterion" which means that he or she has been exposed to an historical event that is considered traumatic. Clinical experience with the PTSD diagnosis has shown, however, that there are individual differences regarding the capacity to cope with catastrophic stress so that while some people exposed to traumatic events do not develop PTSD, others go on to develop the full-blown syndrome. Such observations have prompted a recognition that trauma, like pain, is not an external phenomenon that can be completely objectified. Like pain, the traumatic experience is filtered through cognitive and emotional processes before it can be appraised as an extreme threat. Because of individual differences in this appraisal process, different people appear to have different trauma thresholds, some more protected and some more vulnerable to developing clinical symptoms after exposure to extremely stressful situations. Although there is a renewed interest in subjective aspects of traumatic exposure, it must be emphasized that exposure to events such as rape, torture, genocide, and severe war zone stress, are experienced as traumatic events by nearly everyone.

The DSM-III diagnostic criteria for PTSD were revised in DSM-III-R (1987) and DSM-IV (1994). A very similar syndrome is classified in ICD-10. Diagnostic criteria for PTSD include a history of exposure to a "traumatic event" and symptoms from each of three symptom clusters: intrusive recollections, avoidant/numbing symptoms and hyperarousal symptoms. A fifth criterion concerns duration of symptoms. One important finding, which was not apparent when PTSD was first proposed as a diagnosis in 1980, is that it is relatively common. Recent data from the national comorbidity survey indicates PTSD prevalence rates are 5% and 10% repectively among American men and women (Kessler et al,1996).

As noted above the "A" stressor criterion specifies that a person has been exposed to a catastrophic event involving actual or threatened death or injury, or a threat to the physical integrity of him/herself or others. During this traumatic exposure, the survivor's subjective response was marked by intense fear, helplessness or horror.

The "B" or intrusive recollection criterion includes symptoms that are perhaps the most distinctive and readily identifiable symptoms of PTSD. For individuals with PTSD, the traumatic event remains, sometimes for decades or a lifetime, a dominating psychological experience that retains its power to evoke panic, terror, dread, grief, or despair as manifested in daytime fantasies, traumatic nightmares, and psychotic reenactments known as PTSD flashbacks. Furthermore, traumamimetic stimuli that trigger recollections of the original event have the power to evoke mental images, emotional responses, and psychological reactions associated with the trauma. Researchers, taking advantage of this phenomenon, can reproduce PTSD symptoms in the laboratory by exposing affected individuals to auditory or visual traumamimetic stimuli (Keane, et. al., 1987).

The "C" or avoidant/numbing criterion consists of symptoms reflecting behavioral, cognitive, or emotional strategies by which PTSD patients attempt to reduce the likelihood that they will either expose themselves to traumamimetic stimuli, or if exposed, will minimize the intensity of their psychological response. Behavioral strategies include avoiding any situation in which they perceive a risk of confronting such stimuli. In its most extreme manifestation, avoidant behavior may superficially resemble agoraphobia because the PTSD individual is afraid to leave the house for fear of confronting reminders of the traumatic event(s). Dissociation and psychogenic amnesia are included among avoidant/numbing symptoms by which individuals cut off the conscious experience of trauma-based memories and feelings. Finally, since individuals with PTSD cannot tolerate strong emotions, especially those associated with the traumatic experience, they separate the cognitive from the emotional aspects of psychological experience and perceive only the former. Such "psychic numbing" is an emotional anesthesia that makes it extremely difficult for people with PTSD to participate in meaningful interpersonal relationships.

Symptoms included in the "D" or hyperarousal criterion most closely resemble these seen in panic and generalized anxiety disorder. Whereas symptoms such as insomnia and irritability are generic anxiety symptoms, hypervigilance and startle are more unique. The hypervigilance in PTSD may sometimes become so intense as to appear like frank paranoia. The startle response has a unique neurobiological substrate and may actually be the most pathognomonic PTSD symptom (Friedman, 1991,).

The "E" or duration criterion specifies how long symptoms must persist in order to qualify for the (chronic or delayed) PTSD diagnosis. In DSM-III the mandatory duration was six months. In DSM-III-R the duration was shortened to one month, where it has remained in DSM-IV.

The new "F" or significance criterion specifies that the survivor must experience significant social, occupational, or other distress as a result of these symptoms.

Since 1980 there has been a great deal of attention devoted to the development of instruments for assessing PTSD. Keane and associates (1987) working with Vietnam war zone veterans have developed both psychometric and psychophysiologic assessment techniques that have proven to be both reliable and valid. Other investigators have modified such assessment instruments and used them with natural disaster victims, rape/incest survivors, and other traumatized cohorts. Research using such techniques has been used in the epidemiological studies mentioned above and in other research protocols.

Neurobiological research indicates that PTSD may be associated with stable neurobiological alterations in both the central and autonomic nervous systems. Psychophysiological alterations associated with PTSD include hyperarousal of the sympathetic nervous system, increased sensitivity and augmentation of the acoustic-startle eyeblink reflex, a reducer pattern of auditory evoked cortical potentials, and sleep abnormalities. Neuropharmacologic and neuroendocrine abnormalities have been detected in the noradrenergic, hypothalamic-pituitary-adrenocortical, and endogenous opioid systems. These data are reviewed extensively elsewhere (Friedman, Charney & Deutch,1995).

Longitudinal research has shown that PTSD can become a chronic psychiatric disorder that can persist for decades and sometimes for a lifetime. Patients with chronic PTSD often exhibit a longitudinal course marked by remissions and relapses. There is a delayed variant of PTSD in which individuals exposed to a traumatic event do not exhibit the PTSD syndrome until months or years afterwards. Usually, the immediate precipitant is a situation that resembles the original trauma in a significant way; (for example, a war veteran whose child is deployed to a war zone or a rape survivor who is sexually harassed or assaulted years later).

If an individual meets diagnostic criteria for PTSD, it is likely that he or she will meet DSM-IV criteria for one or more additional diagnoses (Kulka, et. al., 1990; Davidson & Foa, 1993). Most often these co-morbid diagnoses include major affective disorders, dysthymia, alcohol or substance abuse disorders, anxiety disorders, or personality disorders. There is a legitimate question whether the high rate of diagnostic co-morbidity seen with PTSD is an artifact of our current decision rules for making the PTSD diagnosis since there are not exclusionary criteria in DSM-III-R. In any case, high rates of co-morbidity complicate treatment decisions concerning patients with PTSD since the clinician must decide whether to treat the co-morbid disorders concurrently or sequentially.

Although PTSD continues to be classified as an Anxiety Disorder, areas of disagreement about its nosology and phenomenology remain. Questions about the syndrome itself include: what is the clinical course of untreated PTSD; are there different subtypes of PTSD; what is the distinction between traumatic simple phobia and PTSD; and what is the clinical phenomenology of prolonged and repeated trauma. With regard to the latter, Herman (1992) has argued that the current PTSD formulation fails to characterize the major symptoms of PTSD commonly seen in victims of prolonged, repeated interpersonal violence such as domestic or sexual abuse and political torture. She has proposed an alternative diagnostic formulation that emphasizes: multiple symptoms, excessive somatization, dissociation, changes in affect, pathological changes in relationships and pathological changes in identity.

PTSD has also been criticized from the perspective of cross-cultural psychology and medical anthropology, because it has usually been diagnosed by clinicians from Western industrialized nations working with patients from a similar background. Major gaps remain in our understanding of the effects of ethnicity and culture on the clinical phenomenology of post-traumatic syndromes. We have only just begun to apply vigorous ethnocultural research strategies to delineate possible differences between Western and non-Western societies regarding the psychological impact of traumatic exposure and the clinical manifestations of such exposure (Marsella, et. al., 1996).

Before closing, it is necessary to discuss treatment. The many therapeutic approaches offered to PTSD patients are presented in Williams and Sommer's (1994) comprehensive book on treatment. The most successful interventions are those implemented immediately after a civilian disaster or war zone trauma. This is often referred to as critical incident stress debriefing (CISD) or some variant of that term. It is clear that the best outcomes are obtained when the trauma survivor receives CISD within hours or days of exposure. Such interventions not only attenuate the acute response to trauma but often forestall the later development of PTSD.

Results with chronic PTSD patients are often less successful. Perhaps the best therapeutic option for mild-to-moderately affected PTSD patients is group therapy. In such a setting the PTSD patient can discuss traumatic memories, PTSD symptoms and functional deficits with others who have had similar experiences. This approach has been most successful with war veterans, rape/incest victims and natural disaster survivors. For many severely affected patients with chronic PTSD a number of treatment options are available (often offered in combination) such as psychodynamic psychotherapy, behavioral therapy (direct therapeutic exposure) and pharmacotherapy. Results have been mixed and few well-controlled therapeutic trials have been published to date. It is important that therapeutic goals be realistic because in some cases, PTSD is a chronic and severely debilitating psychiatric disorder that is refractory to current available treatments. The hope remains, however, that our growing knowledge about PTSD will enable us to design more effective interventions for all patients afflicted with this disorder.

We regret that we were unable to obtain permission to include the text of the DSM-IV criteria for PTSD with this article.


Davidson, J.R.T., & Foa, E.B (Eds.) (1993). Posttraumatic Stress Disorder: DSM-IV and Beyond. Washington, DC: American Psychiatric Press.

Foa, E.B., Zinbarg, R., & Rothbaum, B.O. (1992). Uncontrollability and unpredictability of post-traumatic stress disorder: An animal model. Psychological Bulletin, 112, 218-238.

Friedman, M.J., Charney, D.S. & Deutch, A.Y. (1995) Neurobiological and Clinical Consequences of Stress: From Normal Adaptation to PTSD. Philadelphia: Lippincott-Raven.

Herman, J.L. (1992). Trauma and Recovery. New York: Basic Books.

Keane, T.M., Wolfe, J., & Taylor, K.I. (1987). Post-traumatic stress disorder: Evidence for diagnostic validity and methods of psychological assessment. Journal of Clinical Psychology, 43, 32-43.

Kessler, R.C., Sonnega, A., Bromet, E., Hughes, M. & Nelson,C.B. (1996). Posttraumatic stress disorder in the National Comorbidity Survey. Archives of General Psychiatry, 52, 1048-1060.

Kulka, R.A., Schlenger, W.E., Fairbank, J.A., Hough, R.L., Jordan, B.K., Marmar, C.R., & Weiss, D.S. (1990). Trauma and the Vietnam War Generation. New York: Brunner/Mazel.

Marsella, A.J., Friedman, M.J., Gerrity, E. & Scurfield R.M. (Eds.) (1996). Ethnocultural Aspects of Post-Traumatic Stress Disorders: Issues, Research and Applications. Washington: American Psychological Association.

Trimble, M.D. (1985). Post-traumatic stress disorder: History of a concept. In C.R. Figley (Ed.) Trauma and its Wake: The Study and Treatment of Post-Traumatic Stress Disorder. New York: Brunner/Mazel.

Williams, M.B., & Sommers, J.F. (Eds.) (1994). Handbook of Post-Traumatic Therapy. Westport, CT: Greenwood Press.

Revised from Encyclopedia of Psychology, ed. R. Corsini (New York, Wiley, 1984, 1994)

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