A large, prospective, population-based study has shown that people who drink no or little alcohol are at increased risk of anxiety and depression.

Data on a sample of 38,390 people taking part in the HUNT study, in Norway, were analysed. Subjects filled in a questionnaire on alcohol intake which was based on the amount of alcohol consumed over the past two weeks. Anxiety and depression were measured using HADS.

The authors found a 'U' shaped relationship between alcohol consumption and anxiety and depression. Both abstainers and heavy drinkers were more likely to report anxiety and depression than mid-range drinkers. In addition 'non-consumers' (defined as non-abstainers who had not drunk any alcohol in the two weeks preceding the questionnaire) were also more likely to report anxiety or depression when compared with moderate drinkers.

Abstention was related to increased odds for both case-level anxiety (1.34, 95% CI 1.19-1.52) and depression (1.52, 95% CI 1.30-1.77).

On further analysis, the study showed that some current abstainers had previously been heavy drinkers. However, while excluding previous heavy drinkers reduced the strength of the association between abstinence and depression and anxiety, it did not completely remove the association.

While the study demonstrates an association between low alcohol consumption and symptoms of anxiety and depression, limitations of the study mean that the causality of the relationship cannot be addressed. Possible causes discussed include a direct protective effect from moderate alcohol consumption, that mid-range drinking habits may be a consequence of psychological wellbeing in cultures where some alcohol consumption is the norm, and confounding from a range of social factors.