Impulsivity involves actions and tendencies that are poorly conceived, premature, unduly risky and often inappropriate in a given context [206], and by extension is related to hyper-sensitivity to immediate reward (delay discounting), the inability to inhibit pre-potent responses (response disinhibition), and risk taking [207]. Impulsivity includes deficits in attention, lack of reflection and/or insensitivity to consequences, all of which occur in addiction (cf. [208]). Evidence suggests that limitations in brain development during adolescence restrict the ability to control impulsivity and may lead to substance use and addiction [209]. Dysfunctional frontal executive functions have often been linked to impulsivity [208] and substance dependence [210]. According to de Wit [207], impulsivity is both a determinant and consequence of drug use. Further, causal connections linking impulsivity, brain development, and risk for SUDs and/or externalizing disorders have been proposed (for reviews, see [202,208,209]). Taken together, the findings of the present study lend support to these etiological propositions. In other words, each of our findings—decreased theta power reflecting possible cortical insufficiency during reward processing along with increased impulsivity and higher rate of externalizing disorders in
