Abstract
BACKGROUND/OBJECTIVES: Evidence suggests a J-shaped association between alcohol consumption and depression, but it remains unclear whether this reflects a true causal effect, reverse causation, or methodological bias. This uncertainty is particularly relevant in older adults, who are at increased risk for both depression and alcohol-related harms. This study aimed to examine the association between varying levels of alcohol consumption and depression risk in community-dwelling older adults. METHODS: We analyzed 16,563 community-dwelling older adults (mean age 75.1 ± 4.6 years) from the ASPirin in Reducing Events in the Elderly (ASPREE) trial. Alcohol intake, reported at baseline and follow-up, was categorized as abstinent, occasional, moderate, or above-guideline. Both intention-to-treat (classified by baseline alcohol consumption, regardless of later changes) and per-protocol (using annual time-updated alcohol consumption ) analyses were performed. To address confounding, informative censoring, and selection bias, we applied marginal structural models with inverse probability weighting. RESULTS: In per-protocol analyses, abstainers (OR 1.17), occasional drinkers (OR 1.11), and above-guideline drinkers (OR 1.15) were significantly associated with a higher risk of depression compared with moderate drinkers, consistent with a J-shaped association. Sensitivity analyses excluding former drinkers and those with baseline depressive symptoms showed similar results. The association remained robust after adjusting for social isolation, social support, social interactions, physical activity, pain, sleep duration, sleep difficulties, and sleep medication use (n = 14,892; Australian sub-sample), and did not differ by sex. CONCLUSIONS: Moderate alcohol consumption was associated with the lowest depression risk, confirming a J-shaped relationship after comprehensive confounder adjustment.