Anxiety Disorders, Obsessive-Compulsive and Related Disorders, Trauma- and Stressor-Related Disorders, and Dissociative Disorders in DSM-5

DSM-5 introduced a number of substantial and clinically relevant changes in the classification of anxiety and related disorders. One of the most striking was the decision to have separate chapters for anxiety disorders, obsessive-compulsive and related disorders, and trauma- and stressor-related disorders. This decision reflects the growing evidence base on the diagnostic validity and clinical utility of these different groupings. Furthermore, adoption of these new groupings helps to explain a number of other changes in DSM-5, including some of the new diagnostic criteria. In this commentary, we also discuss the chapter on dissociative disorders, whose placement next door to the chapter on trauma- and stressor-related disorders is consistent with guiding principles for the overall organization of DSM-5 chapters.

The DSM-5 chapter on anxiety disorders comprises separation anxiety disorder, selective mutism, specific phobia, social anxiety disorder (social phobia), panic disorder, agoraphobia, generalized anxiety disorder, substance/medication-induced anxiety disorder, anxiety disorder due to another medical condition, other specified anxiety disorder, and unspecified anxiety disorder. Each disorder in this chapter is characterized by excessive fear and anxiety as well as related behavioral disturbances, including avoidance symptoms. However, the anxiety disorders differ from one another insofar as each has a different mean age of onset (the chapter is arranged from earlier onset to later onset, as is generally the case across DSM-5), symptoms are precipitated by different situations or objects, and most are characterized by cognitive ideation that differs across disorders.

Despite these differences, DSM-5 diagnostic criteria for anxiety disorders typically have close parallels, with greater consistency than in DSM-IV. The criteria highlight marked fear or anxiety symptoms, the specific thoughts associated with these symptoms, their disproportionate and persistent nature, consequent distress and impairment, and that symptoms are not attributable to physiological effects of a substance or another medical condition, and are not better explained by the symptoms of another mental disorder. These similarities reflect important parallels in the assessment and management of these prevalent and often disabling disorders.

The new DSM-5 chapter on obsessive-compulsive and related disorders contains some of the most substantial changes in the manual, including two new disorders: hoarding disorder and excoriation (skin-picking) disorder. The other disorders in this chapter are obsessive-compulsive disorder (OCD), body dysmorphic disorder, trichotillomania (hair-pulling disorder), substance/medication-induced obsessive-compulsive and related disorder, obsessive-compulsive and related disorder due to another medical condition, other specified obsessive-compulsive and related disorder, and unspecified obsessive-compulsive and related disorder. Some of these disorders are characterized by obsessions or preoccupations as well as by consequent repetitive behaviors or mental acts, whereas others are characterized primarily by recurrent body-focused repetitive behaviors (i.e., hair pulling and skin picking) and repeated attempts to decrease or stop these behaviors.

As in the anxiety disorders chapter, there are some parallels in the diagnostic criteria and specifiers across these disorders; for example, OCD, body dysmorphic disorder, and hoarding disorder may be specified as having good or fair insight, poor insight, or absent insight/delusional disorder-related beliefs. These parallels are intended to encourage particular approaches to assessment and treatment. Of note, the new insight specifier highlights the fact that individuals with obsessive-compulsive and related disorders and poor or absent disorder-related insight should not be diagnosed with a psychotic disorder and should be managed using evidence-based treatments for the obsessive-compulsive and related disorders rather than for psychotic disorders.

The DSM-5 chapter on trauma- and stressor-related disorders is another new chapter that includes disorders that were dispersed throughout DSM-IV. This chapter includes reactive attachment disorder, disinhibited social engagement disorder, posttraumatic stress disorder (PTSD), acute stress disorder, adjustment disorders, other specified trauma- and stressor-related disorders, and unspecified trauma- and related-disorders. These disorders are characterized by a precipitating exposure to a traumatic or stressful event. Although other disorders in DSM may be precipitated by a traumatic or stressful event, the disorders in this chapter differ in that a trauma or stressor is required for the disorder’s onset (although genetic and neurobiological factors also play a role). However, these disorders differ in a number of ways, including the type of precipitating event and the duration and pattern of symptoms. For example, social neglect or deprivation are present in both reactive attachment disorder and in disinhibited social engagement disorder, but the former is characterized by internalizing symptoms and the latter by externalizing symptoms.

Establishing this as a new, separate chapter—and moving PTSD and acute stress disorder from the anxiety disorders—reflects a great deal of evidence that anxiety is only one of several emotional responses to trauma and other adverse events. For example, whereas some individuals with a trauma- and stressor-related disorder may exhibit anxiety- or fear-based symptoms, other individuals may instead, or in addition, display anhedonic and dysphoric symptoms, externalizing anxiety and aggressive symptoms, or dissociative symptoms. Classifying these disorders in a way that emphasizes that a traumatic or stressful event is a required diagnostic criterion encourages clinicians to assess these events and use appropriate trauma- and stressor-based treatments.

Dissociative disorders include depersonalization/derealization disorder, dissociative amnesia, and dissociative identity disorder. Dissociative symptoms are characterized in DSM-5 by “a disruption of and/or discontinuity in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control, and behavior.” Placement of the dissociative disorders chapter next to the trauma- and stressor-related disorders chapter is based on considerable evidence that traumatic experiences, especially in childhood, predispose individuals to dissociative symptoms. Indeed, dissociative symptoms are included in the diagnostic criteria for posttraumatic and acute stress disorders. On the other hand, the association between trauma exposure and dissociative disorders is variable, and these disorders may occur without prior trauma exposure (1). Thus, the dissociative disorders are classified in a separate chapter but one that immediately follows trauma- and stressor-related disorders. This juxtaposition is intended to underscore similarities among some disorders in these two chapters and to stimulate further research on the relationship between traumatic exposure and the development of dissociative disorders.

The order of diagnostic categories has more meaning in DSM-5 than in DSM-IV. The fact that anxiety disorders follow depressive disorders, that obsessive-compulsive and related disorders follow anxiety disorders, and that dissociative disorders follow trauma- and stressor-related disorders is intended to emphasize the close relationships among some of the conditions in these contiguous chapters (2). However, it is important to emphasize that even within each of these DSM-5 chapters, disorders have substantive differences across many validators, such as their neurobiology and treatment. Thus, for example, not all medications useful for panic disorder are efficacious in social anxiety disorder. While any particular classification approach to these disorders has pros and cons (2), the DSM-5 approach is based on multiple studies of diagnostic validity (3–6) and should optimize clinical utility and lead to better patient care. We also believe that these revisions in DSM-5 meta-structure will stimulate important research which, in turn, will inform future iterations of the diagnostic classification.