This study has several limitations that warrant consideration. It is important to note that because the family high-risk paradigm was employed, the findings may not be representative of the general population. It is noteworthy, however, that results obtained in previous studies conducted on this sample concur with findings obtained by others pertaining to genetic, neurophysiological, and psychological antecedents of SUD (Habeych, Charles, Sclabassi, Kirisci, & Tarter, 2005; Vanyukov et al., 2004; Feske et al., 2008). In addition, it is important to point out that the outcomes in this study were confined to AUD and CUD. Furthermore, attrition occurred more frequently in females, the low SES segment of the sample, and participants having lower IQ (albeit still in the normal range). Hence, an attrition bias cannot be entirely ruled out. Lastly, AUD and CUD were evaluated only up to age 22. Whereas epidemiological (Le Strat, Grant, Ramoz, & Gorwood, 2010) and genetic (Chen et al., 2011) research indicates that age 22 is the optimum cutoff for manifesting the early onset variant of SUD, usually referred to as Type II (Cloninger et
