Approximately 10.3 percent of U.S. adults appear to have problems with drug use or abuse during their lives, including 2.6 percent who become drug dependent at some point.
Rates of abuse and dependence tended to be higher among men, Native Americans, those age 18 to 44, lower socioeconomic groups, those living in the West and those who were not married.
Drug abuse refers to the intense desire to take drugs at the exclusion of other activities, and dependence occurs when the body becomes physically dependent on an illicit substance.

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from www.newswise.com/articles/view/529696/