The Influence of Comorbid Negative Mood on Craving’s Relationship to Post-treatment Alcohol Use

ii ABSTRACT Alcohol is ranked as the third highest burden of disease worldwide and the eighth highest leading cause of death. An estimated 19.5% of Australians consume alcohol in quantities that place them at risk of alcohol-related injury or disease over their lifetime. Alcohol misuse is also highly problematic, being associated with a range of negative physical, psychological and social consequences. While treatments are effective in helping people to achieve reductions, relapse rates are high, with up to 80% of treated alcohol users eventually relapsing. The ability to identify which treatment seekers may be at greater risk for relapse would enable appropriate tailoring of interventions and planning of aftercare. Craving has been widely studied as a potential predictor of relapse, but has performed inconsistently. The effect of comorbid depression on craving's predictive performance however, has been largely neglected, despite demonstrated associations between negative affect and craving, and between negative affect and substance use. The aim of this thesis was to explore the performance of craving as a predictor of post-treatment alcohol use outcomes in the presence of comorbid depressed mood, under the hypothesis that presence of negative affect would augment effects of craving, strengthening its predictive power and increasing vulnerability to post-treatment relapse. Two studies were conducted, one with a sample of drinkers with comorbid depression, and the other with a sample of drinkers with a range of depression severity. Study 1 included 284 males and females who self-referred for a randomised controlled trial of treatments for comorbidity of depression with alcohol use. Abstract iii least two occasions in the previous month of greater than 6 standard drinks (6 x 10g ethanol) for men, or greater than 4 for women. Craving was measured prior to treatment using the obsessive subscale of the Obsessive Compulsive Drinking Scale. Two drinking outcomes, average weekly drinks and frequency of alcohol binges, were assessed 18 weeks and 12 months post-baseline. Interaction effects between craving and depression were examined by including an interaction term in the analyses. Craving was found to be a significant predictor of 18-week average weekly drinking and of higher frequency of binges at 18 weeks and 12 months. Neither depression by itself, nor the interaction of depression with craving were significant, although this may have been due to lack of sufficient spread in depression scores to detect an effect. Item analysis suggested different influences of craving over time, with items pertaining to …