A New Classification System

The newly released Diagnostic and Statistical Manual of Mental Disorders (DSM-5) has made a number of modest alterations to the previous DSM-IV, but at the core it remains a dictionary, describing clusters of symptoms, to ensure clinicians and researchers use the same terms in the same way. The fundamental weakness of the DSM remains, and that is, scientific validity. Unlike most other disciplines in the medical fields, diagnoses of mental disorders are based on a consensus about clusters of symptoms, and not on objective, measurable variables. It is akin to making a diagnosis based on the quality of chest pain as described by the patient, rather than on a 12-lead ECG, blood tests for cardiac enzymes, etc. Certainly the symptom of chest pain is the prompt and guide for further objective tests to validate a diagnosis of Left Ventricular Failure, for example, but not definitive enough to draw a diagnosis and subsequent treatment on its own.

The National Institute of Mental Health in the USA has undertaken the Research Domain Criteria (RDoC) project to bring mental health diagnoses into a scientifically validated framework as it is with other areas of medicine. The RDoC will incorporate genetics, imaging, cognitive science, and other levels of information to identify biological markers that will be the foundation of a new classification system. Furthermore the RDoC will not be looking to the definitions of the DSM in an attempt to find a validating science for those definitions, but rather start from the ground up, classifying mental disorders from the neural and genetic patterns that will be identified.

This project is a very ambitious undertaking to say the least. We do not yet have all the data to map mental processes, clearly identify biological markers, and define mental disorders accordingly—but we are on our way. The RDoC is a framework designed to push research along these lines of investigation, and the NIMH is now orienting research funding away from DSM categories and toward studies that look across current categories to identify biomarkers for specific symptoms. Generally research follows the money, so we can expect a significant amount of momentum toward a new diagnostic paradigm for mental health over the next few decades.

What we are likely to see is the emergence of new genetic and neuroscientific data, unshackled from current diagnostic categories, paint a more detailed and specific picture of biological underpinnings of symptoms. Like little building blocks, these specific, measurable biological functions (called “constructs” by RDoC) will be the fundamental unit of analysis. The RDoC have identified seven classes of variables that will be measured in defining these constructs, they are genes, molecules, cells, neural circuits (a core class of variability), physiology, behaviors, and self-reports. Related findings (constructs) will be grouped together into domains of functioning. The RDoC have specified five of these domains: Negative Valence Systems (eg., Fear: amygdala, hippocampus, interactions with vmPFC); Positive Valence Systems (eg., Approach Motivation: mesolimbic dopamine pathway) ; Cognitive Systems (eg., working Memory: dlPFC, other PFC areas); Systems for Social Processes (eg., Social dominance: distributed cortical activity, mesolimbic dopamine systems, testosterone, serotonin); and Arousal/Regulatory Systems (eg., Stress Regulation: raphe nuclei circuits; serotonin).

The RDoC is also taking into account the critical aspect of developmental and environmental aspects of mental disorders. As we are well aware from our neuropsychotherapeutic orientation, neurodevelopment is critical in understanding the emergence of mental disorders in conjunction with environmental interaction/experience. These critical dimensions will make up part of the matrix of measurable findings, and I personally believe (because of early attachment theory) not just another dimension, but rather the canvas on which the other constructs are painted.

So what will this new diagnostic paradigm do to psychotherapy? I believe it will orientate the psychotherapist to read symptoms in a way that gives them clues as to what the underlying neurobiological processes are and what the neurodevelopmental history has been. Accessible and affordable tools to verify these underlying processes may be a few years away yet, but the principles of diagnosis from a matrix of measurable variables is dawning. Given an understanding of what is happening in a client, on a neurobiological level, can only lead to more refined treatment plans and hopefully better outcomes more often. We, as therapists, will still have to be empathic, congruent and skilled in creating a ‘safe’ therapeutic alliance—these basic requirements for good therapy are being increasingly validated by neuroscience. But what we will add to our skill-set, is a diagnostic approach that identifies exactly (or at least with increasing accuracy) what’s happening under the hood, and not relying solely on a noise coming from the engine.

I believe talking therapy to effect neurobiological change will be increasingly substantiated by this new wave of research, further establishing psychotherapy as a front-line intervention for mental disorders. Welcome to a very exiting paradigm shift!


Source Information: National Institute of Mental Health

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