Substance use during early adolescence remains a considerable public health concern. According to recent data, 33%, 19% and 16% of U.S. 8th graders, ages 13-14 on average, report lifetime use of alcohol, cigarettes, and cannabis, respectively (Johnston et al., 2012). In addition to immediate risks of harm, such as unintentional accidents, sexual risk-taking and other victimization (Hingson and Winter, 2003), early use has been linked to both initiation and escalation in use of harder substances (Fergusson et al., 2006; Kandel et al., 2006). Given that age at first use is strongly predictive of alcohol and other drug use disorders (Anthony and Petronis, 1995; Grant and Dawson, 1997), including severity and duration of disorder (Hingson et al., 2006), identifying risk-factors for early initiation is essential for targeted substance abuse prevention.
