Additionally, recent work has begun to examine whether the genetic and environmental risk factors for substance use are substance specific. In general, the results indicate that risk for substance use is not substance specific but places individuals at risk to use a wide range of substances (Tsuang et al. 1998; Kendler et al. 2003; Young et al. 2006). Moreover, this general vulnerability impacts across substances classes (Han et al. 1999; Young et al. 2006; Kendler et al. 2007). Importantly, this general vulnerability has yet to be examined developmentally.
