We have reviewed evidence from both nonhumans and humans indicating that impulsivity is a predictor of early alcohol use. Although there is evidence in both nonhumans and humans that certain indices of impulsive behavior are related to initiation of alcohol use, the studies vary widely in their methodologies. In particular, they utilize very different measures of impulsivity, both within the dimensions we identified above and also across dimensions. Thus, although poor response inhibition (e.g., the IMT and DMT tasks; Dougherty et al., 2004), greater delay discounting, and in humans, self-report measures of impulsive personality are all related to early alcohol use, few studies use more than one measure, making it difficult to integrate the different findings across species, tasks, and measures of alcohol consumption. Similar problems exist in the self-report assessments. For example the relationships among measures such as the EIQ, BIS, different variations of the BIS, and the MPQ are poorly understood. In the future, it would be valuable for authors to justify clearly their selection of measures, including behavioral tasks, self-report measures, and measures of alcohol consumption, and to integrate their findings with the larger literature.
