The Diagnostic and Statistical Manual of Mental Disorders (DSM), a frequently referenced manual of clinical diagnosis published by the American Psychiatric Association (APA), has been called the “Bible” for the field of clinical psychology. Consistent with its prominent role in diagnosis and treatment considerations, research on mental health has traditionally focused on the DSM’s classification system with a focus on categories of disorders. However, following the publication of DSM-5, the National Institute of Mental Health (NIMH) announced that it would make decisions about which research proposals to fund according to a new initiative called the Research Domain Criteria Project (RDoC). The decision marks a paradigm shift in mental health research with important implications for the progress of scientific discovery.
Why did the NIMH introduce RDoC? 

DSM classification relies heavily on symptoms and has yet to interface with recent scientific breakthroughs in genomics and neuroscience. Despite important discoveries about the causes of aberrant behavior, biological findings on psychopathology tend to lack specificity. For example, alterations in a given neural circuit often characterize multiple disorders, or they differ among subgroups with the same disorder. Heterogeneity within categories and high rates of comorbid diagnoses suggest that discrete categories of disorders as they currently exist do not accurately reflect nature. Thus, despite the utility of the DSM in clinical assessment and treatment, the reliance on its categories for research may hinder progress in identifying biological phenotypes. In an effort to bridge the gap between advances in scientific methods and classification of mental disorders, the NIMH launched the RDoC initiative to motivate research that will contribute to a more “biologically valid” framework for understanding mental disorders. By deconstructing current categories, research can focus on the shared cognitive and biological features that underlie psychopathology.

If RDoC does not use the DSM-5 categories, how will it conceptualize mental function?

RDoC focuses on five domains that are central to mental function (and often implicated in clinical disorders) – negative valence systems, positive valence systems, cognitive systems, systems for social processes, and arousal/regulatory processes. The initiative takes a dimensional perspective that integrates many levels of analysis (e.g., genes, molecules, cells, neural circuits, physiology, behavior, and self-report). For example, identifying the genetic, neural, and physiological mechanisms underlying deficits in emotion regulation would cut across different disorders characterized by dysregulated affect, such as anxiety and depression. Identifying the mechanisms underlying these more fine-grained constructs offers an innovative approach to discovering the nature and causes of mental disorders.

How will RDoC change research?

RDoC has immediate implications for research, as it redefines the scientific agenda supported by the NIMH. While prior studies have often focused on specific disorders, the RDoC framework necessitates changes in study design and conceptualization. For example, now it may be more appropriate to include all patients seeking treatment at a clinic for anxiety, as opposed to separately studying patients with generalized anxiety disorder or specific phobia. Another approach may be to select research samples based on biological criteria related to the process of interest. For example, research on neural dysfunction associated with impaired fear extinction might identify participants who surpass a threshold related to amygdala connectivity. In other words, comorbidity is less likely to be grounds for exclusion and may even increase statistical power to answer certain questions within this new paradigm.

Will RDoC compete with the DSM-5?

DSM-5 and ICD-10 remain the standards for diagnosis, and the NIMH and APA have issued a joint statement of their intentions for RDoC and DSM-5 to serve complementary roles. However, RDoC findings could inform future iterations of the DSM. For example, research stemming from RDoC may identify new subtypes of current disorders or even lead to the incorporation of new disorders that cut across current diagnostic categories. As evidence on the relationships between genes, the brain, and behavior becomes stronger, it can be expected to inform future classification systems.

See statement from Dr. Thomas Insel, Director of NIMH, and Dr. Jeffrey Lieberman, President-elect of APA.

Will RDoC lead to better treatments?

RDoC and its potential to advance clinical science have implications for treatment. For example, identifying biological indicators may enhance personalized medicine and provide insight into the best treatment for a given individual. Moreover, randomized clinical trials will increasingly focus on mechanisms, such as a relevant neural circuit, to inform treatment response. Finally, research from RDoC may yield novel targets for intervention, enhancing the translation of clinical research into practice.

Read more about RDoC here.