Moderate alcohol consumption and depression - a longitudinal population-based study in Sweden.

BACKGROUND AND AIMS: The inter-relationship between alcohol consumption and depression is complex and the direction of the association is unclear. We investigated whether alcohol consumption influences the risk of depression while accounting for this potential bi-directionality.

METHODS: A total of 10,441 individuals participated in the PART study in 1998-2000; 8,622 in 2001-2003 and 5,228 in 2010. Participants answered questions on their alcohol consumption, symptoms of depression, childhood adversity, and sociodemographic, socioeconomic, psychosocial and lifestyle factors. A total of 5,087 participants provided repeated information on alcohol consumption. We used marginal structural models to analyze the association between alcohol consumption and depression while controlling for previous alcohol consumption and depressive symptoms and other time-varying confounders.

RESULTS: Non-drinkers had a higher depression risk than light drinkers (≤7 drinks/week) (risk ratio: 1.7; 95% confidence interval 1.3-2.1). Consumers of 7-14 drinks/week had a depression risk similar to that of light drinkers. Hazardous drinking was associated with a higher risk of depression than non-hazardous alcohol consumption (risk ratios: 1.8, 95% confidence intervals: 1.4-2.4).

CONCLUSION: Light- and moderate alcohol consumption and non-hazardous drinking were associated with the lowest risk of subsequent depression after accounting for potential bi-directional effects. Hazardous drinking increased the risk of depression. This article is protected by copyright. All rights reserved.