Posttraumatic stress and alcohol use motives: A test of the incremental and mediating role of distress tolerance

The frequent co-occurrence of trauma exposure and posttraumatic stress disorder (PTSD)with alcohol use problems has been well documented (Langeland & Hartgers, 1998; McFarlane, 1998; McFarlane et al., 2009; Stewart, 1996). Epidemiological studies have found that approximately 51.9% of men and 27.9% of women with lifetime PTSD also meet criteria for lifetime alcohol abuse or dependence, as compared to 24.7% of men and 10.5% of women without lifetime PTSD (Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995). Conversely, alcohol use disorders have been related to more severe posttraumatic stress symptoms in trauma-exposed samples both with and without the PTSD diagnosis (Back, Sonne, Killeen, Dansky, & Brady, 2003; Stewart, Conrod, Pihl, & Dongier, 1999). One initial line of work, focused on better understanding the mechanisms underlying the co-occurrence of these clinical problems, has indicated that trauma-exposed individuals with and without PTSD may demonstrate an enhanced motivation to drink alcohol to cope with negative affective states (Dixon, Leen-Feldner, Ham, Feldner, & Lewis, 2009; Stewart, Conrod, Samoluk, Pihl, & Dongier, 2000; Stewart, Mitchell, Wright, & Loba, 2004; Ullman, Filipas, Townsend, & Starzynski, 2006). Consistent with this perspective, self-reported drinking to cope with negative affect is significantly associated with severity of PTSD symptoms (Ullman et al., 2005). Other work has found that trauma-exposed individuals with alcohol dependence report increased alcohol cravings in the presence of trauma cues (Coffey et al., 2002), suggesting that trauma cues and related negative affect may serve as conditioned stimuli for alcohol use. Despite evidence of relations between posttraumatic stress symptoms, defined broadly, and coping motives for alcohol use, the potential mechanisms underlying this association remain unclear. Distress tolerance is a promising construct worthy of further empirical attention within this realm because of its documented associations with both alcohol use (Daughters, Lejuez, Kahler, Strong, & Brown, 2005; Simons & Gaher, 2005) and posttraumatic stress (Vujanovic, Bernstein, & Litz, 2011). Distress tolerance is defined as the perceived ability to withstand emotional distress (Simons & Gaher). Distress tolerance has been inversely associated with (a) increased alcohol use and related coping motives (Buckner, Keough, & Schmidt, 2007; Simons & Gaher; Simons, Gaher, Oliver, Bush, & Palmer, 2005) as well as (b) elevated post-traumatic stress symptoms (Marshall-Berenz, Vujanovic, Bonn-Miller, Bernstein, & Zvolensky, 2010; Vujanovic, Bernstein, et al., 2011; Vujanovic, Bonn-Miller, Potter, Marshall-Berenz, & Zvolensky, 2011). Although empirically unclear, it is possible that greater posttraumatic stress symptoms may contribute to lower levels of tolerance for distressing emotions. Such lower distress tolerance, in turn, may contribute to increased motivation to use alcohol to cope with negative mood states. As of yet, it is empirically uncertain whether distress tolerance is related to coping motives for alcohol use among trauma-exposed individuals, or whether such a relation is better explained by other factors known to co-occur with alcohol use problems and posttraumatic stress (e.g., difficulties in regulating emotion). Furthermore, no empirical work has attempted to investigate the mediational model described previously wherein distress tolerance partially explains the association between posttraumatic stress symptom severity and coping motives for alcohol use (see Figure 1). Figure 1 Proposed model: Distress tolerance as mediator of the association between posttraumatic stress symptom severity and alcohol use coping motives. Together, the present investigation sought to extend the existing literature with two lines of related inquiry. First, the incremental validity of distress tolerance in terms of alcohol use coping motives, within a trauma-exposed community sample of adults, was examined. It was hypothesized that distress tolerance, as indexed by the Distress Tolerance Scale (Simons & Gaher, 2005), would be incrementally (inversely) associated with alcohol use coping motives, beyond the variance contributed by posttraumatic stress symptom severity, difficulties in emotion regulation, alcohol consumption, and other (noncriterion) alcohol use motives. Alcohol consumption (cf. alcohol use problem severity) was selected as a covariate because the sample was not composed of individuals with alcohol use problems, exclusively. Moreover, this approach to measuring alcohol is consistent with past research and therefore facilitates greater comparability across extant work (Stewart et al., 1999). Based on past work (e.g., Simons & Gaher), significant associations were not expected between distress tolerance and noncoping alcohol use motives (i.e., Social, Enhancement, Conformity motives). Second, contingent on a significant incremental association between distress tolerance and alcohol use coping motives, the potential mediating role of distress tolerance in the relation between posttraumatic stress symptom severity and alcohol use coping motives was explored. Here, it was hypothesized that distress tolerance would mediate the association between posttraumatic stress symptom severity and alcohol use coping motives.