Should there be both categorical and dimensional criteria for the substance use disorders in DSM-V?

Aims As discussed in the following literature review, the relative advantages of categorical and dimensional criteria for classifying the substance use disorders (SUDs) have been debated for many years. The scheduled revision of the Diagnostic and Statistical Manual (DSM) offers an opportunity to re-examine this question. Both categorical and dimensional approaches to diagnosis offer advantages, both may in fact be necessary for a comprehensive taxonomy. Methods One means of resolving debate about the direction to take in revising DSM-V and simultaneously of achieving maximum taxonomic utility is to include both categorical and dimensional criteria in DSM-V. This could be accomplished by first defining a set of categorical criteria, as in the previous editions of the DSM. Corresponding dimensional criteria could then be created using a more empirical methodology. In this paper we review some of the relevant literature, offer a specific proposal for a dimensional component for the DSM-V substance use disorders that also preserves the categorical definitions and suggest areas for additional research relevant the this agenda. Results There is evidence that alcohol and other forms of substance abuse and dependence are heterogeneous categories and that the SUDs can be conceptualized viably as arrayed along a continuum. Amplifying clinically derived categorical definitions with more empirically derived dimensional components to better capture this variability is a particularly important consideration for a substance use research agenda for DSM-V. Conclusions It is crucial that a dimensional approach be offered in some form in DSM-V; but it is also vital that any dimensional approach be linked to the categorical definition. The proposal offered herein provides a model for amplifying categorical definitions with a dimensional component in a way that is evolutionary and not disruptive to the existing taxonomy.