Our finding shows that all BIS impulsivity scores were among the top variables that classified individuals with AUD from the CTL group. The AUD group also showed significantly increased impulsivity compared to the controls. This finding supports the existing view that impulsivity is a core feature of substance use disorders and may result from impaired inhibitory control [35]. We have also observed that six of the top FC variables showed significant correlations with one or more BIS scores (Figure 6). These findings can be supported by earlier studies that have drawn etiological connections among AUD, externalizing traits such as impulsivity, and neural disinhibition in the form of electrophysiological features (e.g., low P3 amplitude and delta and theta oscillations underlying P3 during cognitive processing, and increased resting state beta power) [34,99,118,119]. Importantly, impulsivity was found to be associated with reduced P3 amplitude in AUD [34] and other externalizing disorders [120,121,122]. The heightened impulsivity observed in the AUD group may also be related to altered FC at the frontal connections in the current study and to the lower volumes observed in frontal
