An earlier age of onset of drinking has been reported to correlate with subsequent higher levels of alcohol consumption, a greater risk for alcohol problems, and a faster progression between the first use and the development of alcohol abuse or dependence (also known as alcohol use disorders, or AUDs) (Dawson et al., 2008; DeWit et al., 2000; Grant & Dawson, 1998; Hingson et al., 2008; York, 2004). However, not all studies agree that it is the earlier age of first drink (AFD) that is the key variable predicting future alcohol problems, with some reports raising the possibility that earlier drinking and higher risks for alcohol and other substance-related problems might each reflect a third characteristic, such as conduct problems, that is the major predictor of the alcohol outcomes (King & Chassin, 2007; Labouvie et al., 1997; Labouvie & White, 2002; McGue et al., 2001b; Prescott & Kendler et al., 1999). Such pre-existing conduct problems are themselves associated with an almost 2.5-fold increased probability of an earlier onset of drinking, and these same characteristics predict a 3-fold or higher risk for
