Day-level mediators of change in a brief motivational intervention for alcohol use and liver health

BACKGROUND: Day-level motivation to limit drinking is theorized to be a proximal mechanism of change in motivational interviewing (MI), but day-level evidence remains limited. This study examined whether brief MI with personalized biobehavioral feedback was associated with changes in daily drinking among adults with alcohol use disorder (AUD), including a subgroup with co-occurring alcohol-associated liver disease (ALD), and whether day-level importance and confidence to limit drinking served as within-person mediators. METHODS: Participants (N = 33; M age = 46.0 [12.55]; 799 day-level observations) completed morning surveys for 28 days, including up to 10 pre-intervention days. Each morning, they reported the prior day's standard drinks and rated that day's importance and confidence to limit drinking on 0-10 scales. Multilevel interrupted time-series models included a pre-intervention slope, an intervention-day level shift, and a post-intervention slope, and tested day-level importance and confidence as mediators of daily drinking outcomes. RESULTS: Daily drinking declined during the pre-intervention period, with no significant intervention-day shifts or post-intervention trends. The intervention-day shift was associated with higher day-level importance of limiting drinking, and higher-than-usual importance and confidence on a given day were associated with fewer planned and actual drinks and lower odds of any and heavy drinking. The intervention-day shift was associated, indirectly, with lower daily drinking through higher same-day importance. CONCLUSIONS: Intensive longitudinal data supported perceived importance of limiting drinking as a proximal mediator of change in brief AUD/ALD interventions, suggesting that frequent, day-level reinforcement of the personal salience of drinking reduction may be a key intervention target.