Etiology of PTSD (original) (raw)

2015, Posttraumatic Stress Disorder

Although most people will encounter a traumatic stressor at least once, and often several times, in their lives, most people who experience a traumatic stressor do not develop PTSD (Breslau, 2002; Kessler et al., 2005; Kessler, Sonnega, Bromet, & Hughes, 1995). Therefore, the question of what causes PTSD cannot simply be answered by referring to its definition: a disorder whose symptoms occur following exposure to a traumatic stressor. In fact, there is controversy as to whether PTSD symptoms really are caused by exposure to traumatic stressors, because all of the symptoms, except for memories, flashbacks, and nightmares of traumatic events, could occur regardless of whether a person has experienced a traumatic stressor. The PTSD symptoms that are not by definition tied to a traumatic stressor-even the two symptoms that are defined as psychological or physical distress due to reminders of past stressful events-actually are also symptoms of other psychiatric disorders as well as of PTSD. Thus, it is important to scientifically examine the assumption that PTSD is caused by exposure to traumatic stressors (Box 3.1). Scientific evidence indicating that PTSD is most likely to occur not just when a traumatic stressor has occurred-but when the objective severity of exposure to traumatic danger or harm is more extreme-provides important (albeit not definitive) support for the view that exposure to a traumatic stressor plays a key role in PTSD, as is discussed later in this chapter (see section on the Impact of Stressor Exposure). In this chapter, a more nuanced view of the causes of PTSD is presented than the commonsense version that PTSD is "caused" simply by exposure to a traumatic stressor. Research demonstrates that PTSD is a "multicausal" phenomenon, meaning that it is the product of a combination of a number of potential causes. Rather than describing the factors that contribute to the development of PTSD as "causes," it is clearer and more factual to describe them as "risk factors" and "protective factors"that is, things that increase a person's risk of developing PTSD and things that reduce (or protect against) the risk of developing PTSD. As you will see, risk factors include not only exposure to a traumatic stressor but also biological, psychological, and social factors that influence whether PTSD will occur and that can protect against (but not necessarily prevent) the development of PTSD (Box 3.2).