Last week, the International Society for Traumatic Stress Studies had its annual meeting in Philadelphia. I was there, and discussions abound about "Criterion A."  Contrary to what its name might suggest, Criterion A is not a vitamin, nor is it a short-course bicycle race. Criterion A defines the types of experiences that are considered traumatic enough to cause post-traumatic stress disorder (PTSD) according to the Diagnostic and Statistical Manual of Mental Disorders (DSM). Criterion A has long been a point of contention, in part because it has significant bearing on who receives a PTSD diagnosis and is eligible for evidence-based treatments covered by insurance.

There are special rules when it comes to PTSD. As opposed to most other disorders in the DSM, for which diagnoses are based on symptoms alone, PTSD requires that a person be exposed to a "potentially traumatic event" and then develop specific symptoms. Criterion A defines what counts as: 1) a potentially traumatic event, and 2) a level of exposure sufficient to cause PTSD. Last May, Criterion A was changed with along with other modifications to the PTSD diagnosis in the new DSM 5.

What are considered potentially traumatic events in the DSM 5? A potentially traumatic event is one that involves "death, threatened death, actual or threatened serious injury, or actual or threatened sexual violence." As with the previous version of the DSM(4), a serious car accident is considered a potentially traumatic event, getting laid off, while highly stressful, is not. The definition of a potentially traumatic event in the DSM 5 is quite similar to that in the DSM 4, but differs in that sexual violence is explicitly named instead of being lumped together with other threats to "physical integrity." This change can be interpreted as a small milestone in breaking the silence about sexual violence and its consequences.  Depending upon the circumstances of the event, 30%-80% of sexual assault survivors develop PTSD—a rape takes place about every six minutes in the United States.

So what about the rules of exposure? Here's where things get more complicated. As with the DSM 4, exposure criteria are met in the DSM 5 if a person directly experiences a potentially traumatic event (i.e., it happens to them) or witnesses it in person (e.g., sees someone get mugged at gunpoint). The DSM 5 makes changes, however, in terms of what constitutes an "indirect exposure" (i.e., learning about a potentially traumatic event).

Extensive research has shown that people sometimes develop PTSD after learning that something horrible has happened to a loved one. For example, a prospective study of parents who lost children to accidents, suicide, or homicide found that 21% of mothers and 14% of fathers had PTSD two years after the death.  While the DSM 5 does not exclude such indirect exposures, it tightens the parameters by specifying that the event experienced "by the close friend or relative" be violent or accidental, not natural. For example, someone's grandfather suffering a heart attack would be considered a potentially traumatic event under DSM 4 criteria, but not DSM 5. This change is one of the major reasons why PTSD prevalence is likely to be slightly lower under the DSM 5 criteria.

Criterion A in the DSM 5 also states that repeated, indirect exposure to the gruesome details of potentially traumatic events can be sufficient to cause PTSD, even if the person who experienced the event was a not a loved one. This mainly applies to people working in professional capacities such as first responders, like firefighters and police, or social workers who learn about the traumas of their clients.

Another change in the indirect exposure criteria was made in regard to audio and visual media.  Exposure to potentially traumatic events via television, internet, video games, and photographs are no longer considered sufficient to cause PTSD. Such exposures can still, of course be highly distressing and produce symptoms of post-traumatic stress, especially among children.

Lastly, a major change to Criterion A in the DSM 5 addresses how people emotionally respond after being exposed to a potentially traumatic event. In order to qualify for a PTSD diagnosis under the DSM 4, a person had to be exposed to a potentially traumatic event and respond with "intense fear, helplessness or horror." This second requirement has been removed from the DSM 5—how a person emotionally responds now has no bearing on whether criteria for PTSD can be met. This change was made because the requirement wasn't particularly useful in predicting PTSD symptoms or treatment outcomes.

Millions of people are exposed to potentially traumatic events, and meet Criterion A, each year. While many go on to develop PTSD, most do not. Risk factors for PTSD are largely beyond a person's control and include things such as pre-existing mental health conditions, childhood trauma, additional life stressors (e.g., poverty), and inadequate social support.

Trauma is an inherently personal experience. Criterion A, and similar rules in the DSM, try to make subjective human experiences fit into objective scientific frameworks. This is a challenging task, and far from perfect, but necessary to advance research that helps prevent, mitigate, and treat the enduring consequences of horrible things that happen in the world.

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