It was found that ERO theta power between HR and LR subjects was statistically significant, and this difference was more robust in males compared to females (Fig 3, Panels A1 and A2). This gender-specific neurophysiological finding in HR subjects is supported by the P3 studies in the literature. For instance, smaller P3 amplitudes in high risk subjects has been reported more often in males [26,135–144] than in females [145,146]. Further, P3 reduction has been shown to be more robust in high risk males than in females (e.g., [147,148]). On the other hand, there are only a few ERO studies on high risk subjects to compare our findings, and gender effect in these studies were either not analyzed [65] or not to be found significant [66]. Nevertheless, it is well-known that the incidence of alcoholism is higher in males than in females, with reports in the United States indicating that both life time and 1-year prevalence rates for alcohol abuse and dependence were more than 2 times higher for males compared to the females [149]. Our finding implicating HR males as
