Identifying core transdisciplinary constructs in addiction has clinical utility.

Abstract

The elucidation of the neuropsychological constructs, including compulsivity, underlying addictive behaviours provides not only a translational perspective on mechanisms for understanding addictions but is also potentially useful in clinical practice. The work by Yücel et al. 1 offers a valuable approach to examining neuropsychological constructs underlying addictive behaviours using Research Domain Criteria (RDoC) 2. The results suggest the involvement of several known RDoC constructs and recommend compulsivity as an additional construct. The emergence of compulsivity as a construct proposed by a panel of experts reflects its usefulness for explaining some features of the addictive behaviours. In fact, in recent years, it has been suggested that compulsivity is a transdiagnostic construct that is implicated in several disorders, such as obsessive–compulsive spectrum disorders, including obsessive compulsive disorder, and behavioural or substance addictions 3. In addition, compulsivity as a construct underlying addiction has been examined in a comprehensive review 4. This review analysed available data according to the RDoC units of analysis (genes, molecules, cells, circuits, physiology, behaviours, self-reports, paradigms) in relation to impulsivity and compulsivity. It is important to define not only the neuropsychological constructs underlying behaviours and mental symptoms, but also the relationships and interactions among them. Indeed, RDoC is conceptualized as a dynamic and evolving framework and changes are expected. Currently, the RDoC is organized into five domains (negative valence systems, positive valence systems, cognitive systems, systems for social processes and arousal/regulatory systems). In this consensus study, five of the six transdiagnostic constructs that were already included in the RDoC, and which have been proposed as primary systems underlying the addictive behaviours, belong to the Positive Valence Systems. This domain has recently been reviewed and, in May 2018, a commissioned working group proposed a significant re-organization of the constructs and subconstructs of the Positive Valence Domain 5. For instance, one of the changes involves the ‘habit’ concept, which had previously been considered to be a construct at the same level as ‘reward learning’, and it is now considered a subconstruct under the construct of ‘reward learning’. This re-organization implies a change in the kind of relationship between these two concepts. In addition, it has been suggested that the neuropsychological constructs are not fully independent and it can be expected that, for instance, individual variations in habit formation may influence other neuropsychological functions, such as compulsivity. A further step in defining the primary neuropsychological functions involved in addictions will be to examine the interactions among them. The relevance of this consensus for clinicians is that it provides a framework that links clinical diagnosis, which is defined by a description of behaviours and mental symptoms, with putative underlying mechanisms that may explain these behaviours and symptoms. Therefore, the modulation of these mechanisms through interventions—either psychological, pharmacological or of any other type—may influence clinical manifestations and allow clinicians to select more specific interventions targeted at the underlying components of the addictive behaviour. Furthermore, it may allow the identification of predictors of outcome. For example, in this consensus the experts have related the compulsivity construct with chronicity, and a recent study found that compulsivity was associated with poorer outcomes in gambling disorders 6. Indeed, future clinical studies that examine the effects of interventions not only on symptoms but also on neuropsychological constructs may yield helpful information on the mechanisms involved in addictions. None.