al. 2007). Thus, in line with the competing neural systems model (Bickel et al. 2007), adolescents can be more susceptible to addictions because their “impulsive” system prevails over the “reflective” executive control system. Indeed, studies using various DD paradigms showed that a greater tendency to discount delayed gratification is associated with substance use in adolescents and young adults (Wulfert et al. 2002; Kollins 2003; Reynolds et al. 2003; Audrain-McGovern et al. 2004; Reynolds 2006; Bickel et al. 2007; Perry and Carroll 2008; Verdejo-Garcia et al. 2008), as well as with psychopathology associated with increased risk for substance use and dependence such as externalizing (aggressive and delinquent) disorders (Krueger et al. 1996) and ADHD (Scheres et al. 2006). Taken together, converging evidence from animal and human studies suggests that addiction liability can in part be mediated by individual differences in the neural mechanisms affecting decision making, such as propensity for impulsive choices.
