Moderating effect of working memory capacity on acute alcohol effects on BOLD response during inhibition and error monitoring in male heavy drinkers

Rationale: While alcohol intoxication is known to increase disinhibited behavior, the degree to which disinhibition occurs appears to depend on a number of factors including executive functioning ability. However, the neural mechanisms by which individual differences in executive functioning lead to variable degrees of disinhibition remain unclear. Objectives: The aim of the current study was to examine the neural mechanisms by which individual differences in working memory (WM) capacity moderate alcohol-induced disinhibition. Methods: Seventeen heavy-drinking males participated in a within-subjects design in which two sessions were completed: an alcohol session (.82 g/kg) and a control session. Participants completed a go/no-go task while undergoing functional magnetic resonance imaging (fMRI) after ingestion of the control or alcohol beverage. WM capacity was measured using an operation span task. Results: Significant interactions of session and WM capacity emerged in contrasts examining successful response inhibition within superior temporal gyrus and unsuccessful inhibition in regions within the default mode network. In all cases, individuals with low WM capacity demonstrated a relative decrease in blood oxygen level-dependent (BOLD) response during the alcohol compared to control session, whereas the high-WM-capacity group demonstrated relative increases in BOLD response in the alcohol compared to control session. Conclusions: Low WM capacity appears to be associated with decreased neural response to signals indicating a need for behavioral control, an effect that may lead to increased difficulty with inhibiting responses and increased negative consequences from alcohol intoxication.