Previous epidemiological studies have found that between one-third to one-half of daily nicotine smokers develop nicotine dependence at some point in their lives (Anthony et al., 1994; Breslau et al., 2001; Dierker et al., 2008; Kandel et al., 1997) and that, within a decade of alcohol, cannabis and cocaine use, 12%-13% develop alcohol dependence, 8% cannabis dependence and 15%-16% cocaine dependence (Wagner and Anthony, 2002a). Several risk factors for the transition from use to dependence have been identified, including being young, male, Black or Native-American, poor, with low levels of educational attained, urban residence, early substance use onset, use of another psychoactive substance, and co-occurrence of a psychiatric disorder (Behrendt et al., 2009; Breslau et al., 2001; Chen et al., 2005; Dawson et al., 2008; Grant and Dawson, 1997, 1998; Kandel et al., 1997; O'Brien and Anthony, 2005; Reardon and Buka, 2002; Wagner and Anthony, 2002a, 2007; Warner et al., 1995).
