Several theories of cortical and subcortical brain development focus on the relative imbalance between subcortical reward systems that mature more rapidly than slowly developing frontal control systems, resulting in poor control over impulsive behavior during adolescence (Casey et al., 2008; Nelson et al., 2002; Steinberg, 2008). These models base their predictions on structural brain imaging studies showing that dorsal and frontal brain areas exhibit a slower course of pruning and myelination than ventral and occipital areas (Gogtay, Giedd, Lusk, Hayashi, Greestein, Vaituzis, et al., 2004; Sowell, Peterson, Thompson, Welcome, Henkenius, Toga, 2003). Indeed, these studies indicate that complete maturation of these frontal areas does not occur until the third decade of life. Based on these models, one would expect that ECF would have only limited ability to control impulsive behavior tendencies in early adolescence. Nevertheless, models of neurobehavioral risk for SUD (Moffit, 1993: Nigg et al., 2004; Tarter, et al. 2003) anticipate that ECF and impulsivity will be inversely related. Consistent with this expectation, an intervention to improve working memory ability in children ages 7 to 12 with ADHD found
