Importantly, stress-related anhedonia was not exclusively associated with depression; blunted reward-related VS reactivity was also indirectly associated problematic alcohol use through stress-related anhedonia and substance-related coping behavior. This indirect association is consistent with previous work demonstrating that coping-related substance use, including alcohol, is predictive of later substance problems (Cooper et al. 1995; Grant et al. 2009; Mezquita et al. 2014) as well as a wealth of addiction literature linking substance use disorders to blunted VS reactivity to non-drug-related reward (Koob & Le Moal, 2001; Volkow et al. 2004; Koob & Volkow, 2010). The data presented here build on recent models suggesting childhood adversity increases alcohol-related problems via coping-related substance use (Mezquita et al. 2014) by documenting that VS reactivity to reward moderates this relationship. That this relationship is associated with both depressive symptoms and problematic alcohol use is consistent with recent work suggesting that a comprehensive one-dimensional vulnerability factor best accounts for risk to develop common forms of psychopathology including mood, anxiety, and substance use disorders as well as thought disorders (Lahey et al. 2012; Caspi et al. 2014).
