The dose-response effects of alcohol on positive and depressed affect in major depressive disorder

Major depressive disorder (MDD) and alcohol use disorder (AUD) commonly co-occur; those with MDD tend to drink more heavily than others. Efforts to regulate mood in MDD may underlie the predisposition for AUD in this population, and mood regulation may require higher alcohol doses. However, the specific aspects of affect impacted by orally-administered alcohol at different doses and timepoints along the blood alcohol concentration (BAC) curve remain unclear among those with MDD. Affect consists of two independent dimensions-positive and negative (including depressed) affect-with MDD involving both low positive and high depressed affect. We investigated the effects of low and moderately high alcohol doses (target M peak BAC levels = .04% and .08%, respectively) on changes over time in positive and depressed affect in people with MDD. Sixty participants (M age = 26.90 years; 58% women) were randomized to one of three beverage conditions (no, low, and moderately high alcohol doses), completed measures of positive and depressed affect, and provided subjective intoxication and BAC measures at five timepoints. A beverage condition x timepoint x affect type interaction revealed more sustained alleviation of depressed affect and enhancement of positive affect in the moderately high than low dose condition. Only the moderately high dose pushed positive affect above depressed affect at all post-drinking timepoints. Results suggest a dose-response relationship of alcohol in improving affect for people with MDD. The more sustained affective consequences of moderately high alcohol doses might reinforce heavier drinking behaviours in those with MDD, placing them at increased risk for AUD development.