Chair, Department of Community Health Sciences (CHS), Professor of Community Health Sciences and Medicine, Boston University Schools of Public Health and Medicine, Section of General Internal Medicine, Department of Medicine, the Grayken Center for Addiction, Boston Medical Center, Boston, MA (RS), Mental Health Service, VA Medical Center, Clinical Professor, Departments of Psychiatry and Population and Public Health Sciences, Boonshoft School of Medicine, Wright State University, Dayton, OH (SCM), Professor of Medicine, Emergency Medicine and Public Health, Director, Program in Addiction Medicine, Yale University School of Medicine, New Haven, CT (DAF), Professor of Psychiatry, Director of Addiction Psychiatry, Department of Psychiatry, Stony Brook University, Stony Brook, NY (RNR).

Send correspondence to Richard Saitz, MD, MPH, Boston University School of Public Health, 801 Massachusetts Avenue, Suite 431, Boston, MA 02118. E-mail: [email protected].

Received 9 February, 2020

Accepted 10 February, 2020

Dr. Saitz is President of the International Society of Addiction Journal Editors (2018–2020), Editor-in-Chief of Journal of Addiction Medicine, associate editor of JAMA, and an editor for the Massachusetts Medical Society and Wolter's Kluwer’ UpToDate. All authors were Editors of ASAM's Principles of Addiction Medicine.

The views expressed in this paper do not necessarily reflect those of the US government or the VA.

This article is an edited version of a chapter that originally appeared in Miller SC, Fiellin DA, Rosenthal RN, Saitz R. ASAM's Principles of Addiction Medicine, 6th Edition. Wolters Kluwer, Philadelphia: 2019. The authors thank ASAM's Descriptive and Diagnostic Terminology Action Group (DDTAG) for work developing policy statements that contributed to the conception of the current paper.