Individual differences in ethanol drinking meal structure are shaped by social environments

Alcohol use disorder (AUD) is marked by substantial heterogeneity in drinking behaviors and health outcomes, underscoring the need for preclinical models that capture interindividual variability. We recently developed open-source capacitive lickometer systems for high-resolution monitoring of mouse fluid intake. Using LIQ PARTI and LIQ HD, we found substantial individual differences in alcohol intake that varied across sex and housing status in C57Bl/6J mice. Here, we conducted an expanded secondary analysis of this continuous access ethanol drinking data to quantify behavioral variability in group- and singly-housed mice. We introduce a fluid “meal” analysis that integrates drinking across ethanol and water sippers to define discrete drinking episodes. Using this approach, we observed sex- and housing-dependent reorganization of drinking structure across group and single-housed settings, with group-housed males exhibiting fewer but faster liquid meals. To further characterize multidimensional drinking patterns, we applied principal component analysis to meal variables and identified a “distributed meal” phenotype defined by more meals, reduced meal size, earlier drinking onset, and higher ethanol preference, that segregates by sex. Considering factors that influence behaviors in a social environment, we next examined whether social hierarchy was associated with these patterns using a tube test dominance assay. Social rank was unrelated to ethanol and meal measures; however, offensive dominance behavior positively correlated with principal component scores in males. Together, these findings demonstrate that high-resolution, longitudinal analysis of ethanol drinking reveals distinct behavioral phenotypes that are associated with key components of social behaviors, providing a potential framework for understanding heterogeneity in AUD-related drinking.