There is ongoing debate in the international bipolar disorders community about the optimal diagnostic and classification criteria for mood disorders. On the one side is the Diagnostic Statistical Manual (DSM), which approaches diagnosis on a mostly categorical basis. On the other side is the National Institute of Mental Health (NIMH)’s Research Domain Criteria (RDoC), which consider a more dimensional approach to mood disorders.
Each approach has a unique influence on issues that inform both clinical practice and research. In the spirit of harmony, the ISBD 2015 invited renowned leaders from both sides to address this issue during a “gentle debate”.
The DSM-5 perspective on diagnosis of BD
Dr David Kupfer, founder of the ISBD and Professor of Psychiatry at the University of Pittsburgh, argued in support of the DSM-5 diagnostic classification system. Bipolar disorders (BDs) were afforded a separate chapter for the first time in the DSM-5, strategically positioned between schizophrenia, and anxiety and depressive disorders. This positioning was largely informed by biological and genetic data suggesting there is more common ground shared between diagnoses of mood disorders than was previously thought.
Also for the first time, the DSM-5 proposed selected shifts from diagnostic categories to dimensions. For many clinicians, these changes represented significant advances for treating people with BDs. Many of the emerging measures and models that were proposed in the DSM-5 are also perceived as dimensional rather than categorical. Considered together, Dr Kupfer proposed that these changes showed a movement towards embracing a more dimensional approach to the classification of mood disorders.
One significant change to the DSM-5 was the relaxation of criteria for mixed mood states. Although mixed states had long been recognized as a common feature of bipolar disorder, Dr Kupfer described a disconnect in the way the concept was defined in previous iterations of the DSM and the way it was being applied clinically. The disconnect contributed to an underestimation of suicide risk in people with mixed states, inappropriate treatment selection, and a failure to distinguish between cases of unipolar and bipolar depression. Dr Kupfer acknowledged that the relaxed criteria for mixed mood states in the DSM-5 have already proven to be “extremely useful in the clinical setting.”
Disappointingly, contributions from the field of neuroscience were not afforded a more prominent role in the DSM-5 classification of bipolar disorders. Dr Kupfer acknowledged that work in the field of neuroscience leading up to the release of the DSM-5 did not have the robust sensitivity and specificity that are needed for establishing threshold levels of diagnostic criteria. Nevertheless, a limited number of biomarkers were included in the DSM-5 diagnostic criteria for bipolar disorder, such as sleep and neurocognitive issues.
The RDoC: a framework for promoting innovative research
Dr Bruce Cuthbert, Director of the RDoC unit at the NIMH, started by offering reassurance that the RDoC are not a competing classification system. Instead, they offer a framework for guiding cutting edge psychopathology research. As such, the RDoC provides an empirical basis for future revisions of the DSM that can better incorporate findings from the neurosciences and behavioural sciences.
The RDoC aims to identify fundamental dimensions that cut across multiple mental health disorders. A criticism of the RDoC is that they are reductionistic and ignore the patient’s experience, but Dr Cuthbert argued that: “The RDoC has the capacity to bring to bear our modern neuroscience advances to the patient’s experience.” He also proposed that the RDoC can be aligned with the experience of clinicians by offering insights into the treatment of symptoms and problems, rather than treating diagnoses.
Caught between two languages and ideologies
While the debate carries on, clinicians are confronted by these two systems on which to base treatment decisions. Dr Kupfer suggested that having two approaches creates a distance between scientists and clinicians, and an uncertain atmosphere for conducting clinical research and for research funding. However, he also recognized opportunities for successful collaboration. Both approaches share the goal of creating a new nosology in which biomarkers and signs – not just symptoms – align with clinical realities.
Whatever the future may hold for diagnostic and classification criteria for BD, one thing is certain: this collegial debate will continue at future meetings of the ISBD. Stay tuned!
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Our correspondent’s highlights from the symposium are meant as a fair representation of the scientific content presented. The views and opinions expressed on this page do not necessarily reflect those of Lundbeck.
