A dimensional option for the diagnosis of substance dependence in DSM-V

In this paper we discuss the creation of dimensional equivalents for categorically defined substance use disorders (SUDs) in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V), which now is being created. We begin with a review of the considerable literature that has accumulated on the dimensional properties of the SUDs. These studies have primarily examined the alcohol use disorders, but work relevant to other substances is reviewed as well. The weight of evidence indicates that SUDs fit well into a unidimensional concept. We next discuss potential advantages, drawbacks, and challenges in developing a dimensional alternative for the SUDs and highlight some issues for an ongoing research agenda to further explore the challenges. Finally we offer a specific proposal for a SUDs dimensional option for DSM-V. The model we propose is based on, and would relate directly back to, the categorical criteria that will be created for the SUDs by the substance use diagnostic workgroup. It is our contention that offering a dimensional equivalent for the DSM-V categories would be of great value, but that the categorical and dimensional definitions should be based on the same symptoms and closely linked. A dimensional scale that does not relate directly to the categorical definition would be counterproductive.