Stabilizing Constructs through Collaboration across Different Research Fields as a Way to Foster the Integrative Approach of the Research Domain Criteria (RDoC) Project

摘要

Introduction More than 450 million people worldwide suffer from neuropsychiatric disorders and the numbers continue to rise (WHO, 2016 ). In 2010, aiming to solve the global mental health crisis and advance psychiatry toward a precision medicine approach, the US National Institute for Mental Health (NIMH) initiated the Research Domain Criteria (RDoC) Project (Cuthbert and Insel, 2013 ). Scientists at NIMH importantly recognize that understanding and explaining psychopathological phenomena requires input from different areas of science that investigate the role of different units of analysis (e.g., genes, cells, systems) in the production of organism-level behavioral functions. The RDoC matrix is put forward as a context for integrating results from these different sciences into a taxonomy of putatively valid constructs they purportedly share in common. It is intended to facilitate the development of “integrative psychobiological explanations” of those behavioral functions designated by the constructs (Cuthbert and Kozak, 2013 , p. 931; See also Sanislow et al., 2010 ). Such explanations, by shedding light on the mechanisms of these functions, will enable investigators to pinpoint viable targets for therapeutic intervention in cases in which these functions are disrupted. The RDoC project is still in its infancy and its proponents recognize that it has much room for improvement (Casey et al., 2014 ). To date, it has been criticized for being “braincentric” and decontextualizing mental disorders from their bodily, social, and environmental contexts (e.g., Whooley, 2014 ; Bernard and Mittal, 2015 ). Although proponents of RDoC claim that one of its crucial aims is to integrate various areas of science, an obstacle to this integration is the lack of construct stability in psychology and neuroscience. In this article, I explain why stabilizing constructs is important to the success of the RDoC initiative and identify one measure for facilitating such stability. The RDoC matrix The RDoC Matrix consists of a table in which findings from psychology and neuroscience may be organized. Five broad domains of behavioral functioning are identified in the rows of the first column of the matrix: (1) positive , (2) negative valence systems , (3) cognitive , (4) social processing , and (5) arousal/modulatory systems . A selection of constructs designating some behavioral functions currently under study across psychology and neuroscience are identified and classified under one of each of the 5 domains. For example, attention, perception, declarative memory, language, cognitive control , and working memory are classified as cognitive systems. Negative valence systems include the constructs of acute threat, potential threat, sustained threat, loss , and frustrative nonreward . Each construct is also given a general definition. In most cases, these definitions make reference to neural, psychological, and behavioral processes associated with the construct. For example, fear is characterized as involving “activation of the brain's defensive motivational system to promote” protective behaviors (i.e., neural processes), “a pattern of adaptive responses to conditioned and unconditioned threat stimuli” (i.e., behavioral/psychological processes) and possibly “internal representations and cognitive processing” (i.e., psychological processes) ( http://www.nimh.nih.gov/research-priorities/rdoc/constructs/acute-threat-fear.shtml ). The columns of the matrix reflect the fact that research on domains of behavioral functioning spans multiple levels of organization from genes to cells to networks to behavior and includes multiple different areas of science (e.g., psychology, systems neuroscience, and neurobiology). An additional column labeled “paradigms” is where experimental paradigms , standard procedures for producing, detecting and measuring behavioral functions that correspond to the constructs in the matrix, are placed. The Stroop Task is an experimental paradigm historically used to investigate selective attention in human subjects. Fear-conditioning paradigms, in contrast, are used to study fear in humans and non-human mammals. How will RDoC facilitate progress in understanding disturbances in behavioral functioning? Investigators working in those sciences represented in the matrix use experimental paradigms to produce, detect and measure instances of behavioral functions that correspond to RDoC constructs. The constructs are essentially labels that are linked up with (1) experimental paradigms used to investigate the behavioral functions designated by those labels and (2) units of analysis that have been implicated in the production of behavioral functions designated by those labels. Although proponents of RDoC remain vague about the details, at some point research findings inputted into the matrix are supposed to result in integrative psychobiological or mechanistic explanations that describe the physical components and processes t