A new paper in Perspectives in Psychological Science looked at all the possible combinations of symptoms that could achieve a DSM-5 diagnosis of posttraumatic stress disorder and found there are now 636,120 ways to have PTSD.
This shows one of the many drawbacks of having a ‘check-list’ approach to classifying mental disorder.
636,120 Ways to Have Posttraumatic Stress Disorder
Perspectives in Psychological Science
November 2013 vol. 8 no. 6 651-662
Isaac R. Galatzer-Levy
Richard A. Bryant
In an attempt to capture the variety of symptoms that emerge following traumatic stress, the revision of posttraumatic stress disorder (PTSD) criteria in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM–5) has expanded to include additional symptom presentations. One consequence of this expansion is that it increases the amorphous nature of the classification. Using a binomial equation to elucidate possible symptom combinations, we demonstrate that the DSM–IV criteria listed for PTSD have a high level of symptom profile heterogeneity (79,794 combinations); the changes result in an eightfold expansion in the DSM–5, to 636,120 combinations. In this article, we use the example of PTSD to discuss the limitations of DSM-based diagnostic entities for classification in research by elucidating inherent flaws that are either specific artifacts from the history of the DSM or intrinsic to the underlying logic of the DSM’s method of classification. We discuss new directions in research that can provide better information regarding both clinical and nonclinical behavioral heterogeneity in response to potentially traumatic and common stressful life events. These empirical alternatives to an a priori classification system hold promise for answering questions about why diversity occurs in response to stressors.
Many argue that psychiatric diagnoses are mostly just descriptions of syndromes: groups of signs and symptoms that tend to group together rather than the result of a single underlying disorder.
Sometimes they are better thought of a convenient classifications for testing treatments against.
When diagnoses are developed, however, there is always the temptation to continually tweak the definition to allow the inclusion or exclusion of different experiences as valid targets for treatment.
These changes are usually well-intentioned but can lead to unintended consequences – as this study shows.
Link to locked paper from Perspectives in Psychological Science.