This shift in the relative importance of nonspecific genetic factors that happens across adolescence is also interesting in that it parallels changes in brain development that occur across this developmental period. The striatal system, which has been related to impulsivity and reward-seeking, is known to mature earlier compared to the prefrontal cortex, which is involved in top-down cognitive control (Casey et al., 2005; Clark and Winters, 2002; Galvan et al., 2006; Giedd et al., 1999; Sowell et al., 2003). This asynchronous developmental pattern is related to increased risk-taking (Steinberg, 2004), preference for immediate over long-term gains, and increased discounting of future negative consequences (Steinberg et al., 2009). Interestingly, the importance of the part of the genetic predisposition on substance use outcomes that reflects general behavioral disinhibition peaks in adolescence at the time when brain development favors risk-taking. Further, this general genetic risk has been shown to decline earlier in females (Meyers et al., 2014; Vrieze et al., 2012), which is consistent with the earlier cortical maturation that takes place in females (Lenroot et al., 2007).
