Drinking Motives Moderate Daily Relationships Between PTSD Symptoms and Alcohol Use

Posttraumatic stress disorder (PTSD) and alcohol dependence (AD) frequently co-occur, although results of both cross-sectional and longitudinal studies evaluating the nature of their relationship have been mixed. There has been varied support for competing models explaining how these conditions influence one another. To assess both the self-medication and mutual maintenance models, as well as examine the potential moderating role of drinking motives, the current study used Generalized Estimating Equations to evaluate daily associations for an average of 7.3 days between PTSD symptoms and alcohol use in a mixed-gender sample of individuals who met criteria for both PTSD and AD. Results generally supported a self-medication model with elevated PTSD symptoms predictive of greater alcohol use on that same day and on the following day. Contrary to a mutual maintenance model prediction, drinking did not predict next-day PTSD symptoms. Results also indicated that both coping and enhancement drinking motives were significant moderators of the PTSD and drinking relationships, suggesting that these relationships may be more or less salient depending on an individual's particular drinking motivations. For example, among those higher on coping drinking motives, a 1-unit increase in PTSD symptom severity was associated with a 35% increase in amount of alcohol consumed the same day, while among those low on coping drinking motives, a 1-unit PTSD increase was associated with only a 10% increase in alcohol consumption. We discuss implications of these findings for the larger literature on the associations between PTSD and alcohol use as well as for clinical interventions.