One of the DSM-V research planning conferences, co-chaired by Drs Eric Hollander and Joseph Zohar, examined which disorders in DSM might be considered for inclusion in an obsessive-compulsive spectrum grouping, based on phenomenology, comorbidity, course of illness, treatment response, genetics, neuroimaging, and other validators.10 They proposed the following candidates for inclusion in the OC spectrum:
• Obsessive-compulsive personality disorder (OCPD)
• Tic disorders
• Sydenham and other pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS)
• Body dysmorphic disorder
• Eating disorders
• Pathological gambling and other behavior addictions
• Substance dependence
Conference participants concluded that the strongest evidence for inclusion in an OC spectrum exists for tics, body dysmorphic disorder, and hypochrondriasis, with less support for hoarding, trichotillomania, PANDAS, and OCPD.
Other areas of change
Another area of likely change in DSM-V concerns current dissatisfaction with its categorical nature: that is, in DSM-IV a person either has or does not have a particular diagnosis. Categorical systems or typologies are the predominant approach used in medical classifications for several reasons. Classifying the world into categories is a fundamental characteristic of human thinking embodied in the nouns of everyday speech (eg, animals, plants, planets, chemical elements).
The yes/no nature of categorical diagnosis also serves to facilitate clinical decision making, which is typically characterized by a number of yes/no decisions (eg, whether to treat, whether to hospitalize). Moreover, it has traditionally been assumed that most medical diseases are discrete entities. However, while this assumption might be true for a few conditions (eg, Down syndrome, fragile X syndrome, Alzheimer disease, Creutzfeldt-Jakob disease), the vast majority of psychiatric disorders exist on a continuum with no discrete boundaries between disorders (eg, schizophrenia and bipolar disorder) and between disorders and normality (eg, depression).
The imposition of arbitrary diagnostic thresholds, as in DSM, leads to high rates of subthreshold and not otherwise specified diagnoses, and high rates of diagnostic comorbidity. For this reason, there has been great interest in incorporating dimensional approaches into DSM-V.11 Such approaches could improve measurement-based care and allow clinicians to provide a dimensional indication of cross-cutting symptoms, such as impulsivity or lack of insight. The challenge for DSM-V will be to figure out how to include dimensions that clinicians will find useful rather than burdensome.12-14
When DSM-V is published in 2012, it will probably be the last of these diagnostic manuals as we know them. The current model for revising DSM is to convene workgroups at certain intervals that will review the scientific literature and propose changes to the definitions of every disorder in the manual based on new findings. The obvious problem with this model is that scientific advances are made all the time—and not at the same rate for each class of disorders.
If a new finding concerning the pathophysiology of schizophrenia renders the definition obsolete, why should a new definition have to wait until the American Psychiatric Association (APA) revises the entire manual? Similarly, for disorders in which there has been little scientific research, the convening of workgroups devoted to proposing changes to the criteria would increase the likelihood that changes will be made unnecessarily.
Although this problem has long been recognized, technical constraints on how changes could be disseminated have kept the APA locked into a traditional model in which (like textbooks) the entire manual is periodically revised. Advances in electronic publishing are on the verge of freeing the APA from this model and may allow changes to be made piecemeal to DSM in response to scientific advances. It is therefore likely that future editions of DSM will be distributed as an electronic document that can be updated as needed.