Objective: Various clinical studies have documented associations between alcohol consumption and depressive disorders. In some circumstances, alcohol ingestion may cause or worsen depression, whereas in other circumstances the direction of causal effect may be reversed. The objective of this study was to evaluate associations between alcohol consumption and major depression in the Canadian population.
Method: Data from the Canadian National Population Health Survey (NPHS) were analyzed. This survey, conducted by Statistics Canada in 1994, used a probability sample of 17,626 subjects. The NPHS included measures of alcohol ingestion and a diagnostic screen for major depression (Composite International Diagnostic Interview [CIDI] Short Form).
Results: Subjects reporting any drinking in the year preceding the interview were more likely to have experienced an episode of major depression during that time than subjects reporting no drinking. Subjects reporting maximal ingestions of 5 or more drinks (and especially 10 or more drinks) on at least 1 occasion during the preceding year were also at greater risk of major depression than nondrinking subjects or subjects reporting smaller maximal ingestions. Neither the average amount consumed daily nor the frequency of drinking was associated with major depression.
Conclusions: In the general population, there is no simple relationship between the quantity or frequency of alcohol consumption and the prevalence of major depression. Any drinking and maximal consumption on 1 occasion, however, are related to the prevalence of major depression. Further research is needed to delineate causal mechanisms so that clinical and public-health interventions can be formulated.