It should also be noted that the proposed sequence applies only to the use of different drugs rather than different levels or extent of drug involvement (from use to dependence) (Kandel and Jessor, 2002) and does not extend to SUD development. Therefore, interestingly, the area of GH application is outside of the medical realm and has only a temporal connection with addiction. These limitations notwithstanding, the GH has significantly influenced policy formation (Leshner, 2002), intervention (Manski et al., 2001), and research (Kandel and Yamaguchi, 1999; Kandel, 2002b). Research, whose purpose is to inform both intervention and policy, may be hindered or misdirected if a concept lacking substance, validity and utility is accorded prominence. In turn, the targets for policy and intervention may be shifted or insufficiently focused to produce an optimal impact.
