Because endophenotypes like the low LR and impulsivity explain only part of the risk for alcohol problems, our group has used Structural Equation Models (SEMs) to evaluate environmental and attitudinal characteristics that might partially mediate how low LR and impulsivity relate to later alcohol problems. SEM-based studies indicated that low LR related to adverse alcohol outcomes both directly and through partial mediation by associating with heavy drinking peers, developing exaggerated expectancies of the positive effects of alcohol, and using alcohol to cope with stress (e.g., Schuckit et al., 2009a, 2010, 2011). Similar models have been evaluated regarding how aspects of impaired impulse control relate to heavy drinking and alcohol problems might be partially mediated by substance using peers, poor coping skills, positive alcohol expectancies and drinking to cope (e.g., Jacob et al., 2009; Jessor and Jessor, 1997; Sher, 1991, Tarter et al., 1999; Zucker et al., 1995). Our group has reported that the impact of impulse control-related characteristics on excessive drinking and related problems was partially mediated by positive alcohol expectancies and drinking to cope, but found less consistent evidence of partial mediation by peer heavy drinking (Schuckit and Smith, 2006).
