Much of what I write about relates to the concept of posttraumatic stress disorder (PTSD), the primary psychiatric disorder that follows from traumatic life experiences. Because PTSD is so central to much of what we talk about in relation to stress and trauma, I believe that this post is needed to provide some clarification for those who have not yet memorized the 20 diagnostic symptoms, and to lay a foundation for future posts.
PTSD, which first appeared in the formal Diagnostic and Statistical Manual (DSM) classification system in 1980, is both highly adopted and under attack at the same time. On the one hand, PTSD has been so well accepted into the lexicon of our culture that books and movies revolve around central characters with PTSD as part of the driving narrative (e.g., American Sniper), or activists try to link their causes to PTSD to gain instant authenticity (see my last blog Stress Is Not Trauma). On the other hand, critics constantly attack alleged flaws of PTSD in order to promote other agendas. So, what exactly is PTSD and how good is it?
The diagnostic criteria for PTSD in the fifth and latest edition of the DSM (DSM-5) consist of 20 possible symptoms that are divided amongst 4 clusters.
5 symptoms in the re-experiencing cluster:
2 symptoms in the avoidance cluster:
7 symptoms in the altered cognitions and moods cluster:
6 symptoms in the increased arousal cluster:
The formal diagnosis is based on an algorithm that requires symptoms from all four clusters.
To qualify for the diagnosis of PTSD, an individual must have at least 1 of the five re-experiencing, 1 of the two avoidance, 2 of the seven altered cognition, and 2 of the six increased arousal symptoms. The algorithm ensures that a variety of different types of symptoms are represented. The algorithm creates a fairly high bar so that minimally symptomatic individuals do not get over-diagnosed. Thus, an individual with the diagnosis can have as few as 6 or as many as 20 of the possible symptoms.
The current diagnostic criteria represent a slight change from the DSM-IV version of PTSD which consisted of 17 possible symptoms divided amongst only 3 clusters. But studies have demonstrated that the changes made to the DSM-5 criteria only slightly, and insignificantly, decreased the rates at which individuals can be diagnosed compared to the DSM-IV. I think the changes made in the DSM-5 were completely unwarranted but that deserves its own post in the future.
The diagnosis of PTSD is one of the most well-validated disorders in all of psychiatry. The diagnosis is reliable between different raters (inter-rater reliability), is distinct from other disorders (discriminant validity), shows stability over time (predictive validity), correlates with neurobiological profiles, and responds to specific treatments (convergent validity).
PTSD is one disorder in the large classification of psychiatric disorders in the DSM-5. The DSM-5, like PTSD, is also both highly adopted and under attack at the same time. The first edition of the DSM was birthed in 1952. The second edition came out in 1968. These first two editions were monumental in their own right, because they gave a formal organization to the classification of psychiatric disorders for the first time, sort of like the first attempts to classify species of animals. But, constrained by the limited information at the time, the descriptions of the disorders did not go into enough details.
The real usefulness of the DSM came into being with the third edition (DSM-III) in 1980 which was vastly redesigned. The major advancement of DSM-III was that the disorders were described in much more detail, or operationalized. Prior to the DSM-III, the disorders were so poorly described that apples could not be compared to apples, researchers could not be reliable with one another, and research was nearly impossible. The DSM-III created a reliable way to define the categories. This reliability allowed researchers in different parts of the world to study the same disorders because they had a reliable way to define them. This helped to fuel an exponential growth in research. The DSM-III was like giving language to a child.
Communication is the greatest strength of the DSM categorical approach. The category names allow researchers to talk to other researches, doctors to talk to patients, and anybody to talk to anybody else about psychiatric problems. The disorder names have intuitive meanings that everyone can understand.
But everybody knows this story. That’s not new. The story is worth retelling often because it seems to get lost in the cacophony of critics looking for a straw man to beat down.
Critics have attacked the DSM because it is a categorical system, and the critics believe that a dimensional classification system would be a far better representation. Yet, no serious dimensional classification system has been proposed.
Critics have attacked the DSM because it only describes symptoms, and does not describe the neurobiological underpinnings of disorders. Yet, no neurobiological classification system has been proposed. The NIMH launched the Research Diagnostic Criteria (RDoC) project in 2009 to try to re-boot a neurobiological approach, but scientists using an RDoC approach have yet to produce a single viable challenge, and I’ll be surprised if they produce anything close to a replacement in my lifetime.
If the DSM is so bad, where are all the superior replacements for the DSM? Turns out, it’s not that easy to come up with something better. Many smart folks have pondered over psychiatric classification, and still the DSM-5 is the only viable classification system in the United States (and the very similar International Classification of Diseases system in other countries).
The DSM, and PTSD, do exactly what they have been intended to do - to provide a reliable method to identify a construct to facilitate communication and research. Consumers, clinicians, and researchers have all benefited. The classifications were never intended to fully represent all the dimensional grayscales of complex life or to illuminate the underlying neurobiology. To criticize the DSM and PTSD paradigms for these shortcomings is like attacking the taxonomy of species because it doesn’t explain how birds fly. Such criticisms reflect perhaps more on the critics than on the paradigms.