This review will give a synopsis of the current understanding of genetic contributions to the vulnerability of substance dependence. There have been extensive discussions about the terminology used to define substance use disorder – “dependence” versus “addiction.” Substance dependence is the official diagnostic nomenclature used in the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 2000) to represent the syndrome of substance misuse that leads to adverse consequences and includes a cluster of symptoms such as tolerance, withdrawal, and inability to stop using (See DSM-IV substance dependence for the complete diagnostic criteria). The creators of DSM-IV criteria selected the term “dependence” because of the concern of stigmatization associated with “addiction.” At this time, revisions to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) are underway for release in 2013. In this revision, issues have again been raised about the term used to define this clinical syndrome. In order to differentiate from the normal physiologic development of tolerance and withdrawal that develops with substance use from the compulsive drug
