The sample consisted of 5438 primary care attenders from 14 countries who participated in the WHO Collaborative Study of Psychological Problems in General Health Care. Alcohol use was assessed using Alcohol Use Disorders Identification Test (AUDIT) and the mental disorders were assessed with the Composite International Diagnostic Interview (CIDI).
Light to moderate alcohol consumption was associated with a lower prevalence of depression and generalized anxiety disorder compared to abstinence while excessive alcohol consumption was associated with a higher prevalence of depression. This non-linear association was not substantially affected after adjustment for a range of possible confounding variables, including the presence of chronic disease and the current physical status of participants and was evident in different drinking cultures.
The study confirms that excessive drinking is associated with an increased prevalence of depression, but also raises the possibility that light/moderate drinking may be associated with a reduced prevalence of both depression and anxiety. Any causal interpretation of this association is difficult in the context of this cross-sectional study and further longitudinal studies are needed.