Major depression in persons with alcoholism has been thought to result from alcohol intoxication and withdrawal effects that mimic depressive syndromes. Although the association between major depression and alcoholism is well established, the reason for this association is not understood. Possible causes of the association may be shared etiology, the direct result of the pharmacology of heavy alcohol consumption, or an indirect link between the outcomes of alcohol abuse that lead to increased risk factors for depression. Establishing the association between major depression and alcoholism can provide physicians who care for these patients with a better understanding of the dual diagnoses. Hasin and Grant evaluated the association between current major depression and past alcohol dependence.

The data reviewed were from the National Longitudinal Alcohol Epidemiologic Survey, which was a nationally representative sample of the U.S. adult population. The study included former drinkers who had not used drugs or smoked within the past year. This group was assessed using a structured interview that asked about symptoms consistent with major depression and alcohol dependence, based on the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) criteria for both disorders. The study group was divided into those who had a history of alcohol dependence, based on DSM-IV criteria, and those who did not, and all subjects were assessed for major depression within the past 12 months. A linear logistic regression analysis tested the association between major depression and alcohol dependence, controlling for other variables.

A total of 6,050 former drinkers participated in the study. Persons with a history of alcohol dependence had a more than fourfold increased risk of major depression. This increased risk was maintained even while controlling for other variables during data analysis. The subjects with major depression had last used substances two or more years before the study. This gap eliminated the possibility that the depression was a direct result of alcohol intoxication or withdrawal effects.

The authors conclude that there is a significant association between previous alcohol dependence and current or recent major depressive disorder. They also state that treatment of depression should not be withheld in recovering alcoholics because of the concern that the symptoms may represent prolonged intoxication or withdrawal effects. Treatment of recovering alcoholics may reduce the risk of relapse.