We have interpreted the present findings to suggest that the risk profile of class 3 may make it less likely that they will mature out of high risk drinking after graduation. Along similar lines, prospective and longitudinal studies have suggested that aspects of behavioral undercontrol/disinhibition predict subsequent substance use problem severity (Littlefield et al., 2010; Mezzich et al., 2007). The cross-sectional nature of this study prevents us from making unequivocal explanations for the observed relationships between behavioral undercontrol/disinhibition and alcohol problem severity. Heavy substance use has also been found to increase disinhibited behavior (Bechara, 2005; Redish et al., 2008; see Leeman et al., 2009a for a discussion of these issues). It is also possible that the significantly earlier age of alcohol use initiation among those in class 3 is critical to their increased level of risk and with additional time, those in class 2 will also see their level of alcohol problem severity rise. Further prospective research is needed to address the merits of these possible interpretations of the present findings.
