Predicting the development of posttraumatic stress disorder from the acute response to a traumatic event

Abstract

Posttraumatic stress disorder (PTSD) is a psychiatric condition that is directly precipitated by an event that threatens a person’s life or physical integrity and that invokes a response of fear, helplessness, or horror. In recent years it has become clear that only a proportion of those exposed to fear-producing events develop or sustain PTSD. Thus, it seems that an important challenge is to elucidate aberrations in the normal fear response that might precipitate trauma-related psychiatric disorder. This paper summarizes the findings from recent studies that examined the acute and longer term biological response to traumatic stress in people appearing to the emergency room immediately following trauma exposure. In the aggregate, these studies have demonstrated increased heart rate and lower cortisol levels at the time of the traumatic event in those who have PTSD at a follow-up time compared to those who do not. In contrast, certain features associated with PTSD, such as intrusive symptoms and exaggerated startle responses, are only manifest weeks after the trauma. The findings suggest that the development of PTSD may be facilitated by an atypical biological response in the immediate aftermath of a traumatic event, which in turn leads to a maladaptive psychological state.

Introduction

According to recent estimates, approximately 18% of all women and 10% of all men in the United States will develop posttraumatic stress disorder (PTSD), defined according to the DSM-IV, at some time in their lives (Breslau et al 1998a). The high prevalence of this disorder reflects not only a fairly violent society in which exposure to events such as rape, child abuse, crime, and other forms of interpersonal violence are common, but also a reasonably dangerous environment that offers several opportunities for exposure to other kinds of man-made (e.g., motor vehicle accidents, plane crashes, or toxic waste exposure) or naturally occurring (e.g., earthquake, flood, avalanche) hazards. About 90% of citizens in the United States are exposed to at least one potentially life-threatening event (as defined by the DSM-IV) in the course of their lives (Breslau et al 1998). A great many individuals are exposed to more than one traumatic event in their lives (Kessler et al 1995).

By definition, PTSD can only be diagnosed following exposure to a traumatic event. According to the most current definition in the Diagnostic and Statistical Manual, 4th edition, a traumatic event is one that “results in a threat of death or physical integrity and in a subjective response of fear, helplessness, or horror” (American Psychiatry Association 1994). This definition states the obvious: that fear is an essential component of the response to an overwhelming, life-threatening event. Based on the prevalence of these events in our society it could easily be concluded that the fear response is something that all persons experience at some time in their lives.