<p>Although alcohol consumption and depression are well-known risk factors for dementia, the effect of alcohol consumption in subjects with depression on the risk of dementia remains unclear. National claim data of South Korea were used in this study. A total of 1,856,078 patients diagnosed with depression who had received health examination within 2&#xa0;years before diagnosis of depression were included. Based on drinking habit and the amount of alcohol consumption, subjects were categorized into three groups: non-drinkers, mild-to-moderate drinkers, and heavy drinkers. The occurrence of dementia (Alzheimer’s and vascular) was determined. Among eligible subjects, 1,246,750 non-drinkers, 504,112 mild-to-moderate drinkers, and 105,216 heavy drinkers were identified. Compared to non-drinkers, heavy drinkers showed an increased risk of dementia (aHR, 1.087; 95% CI, 1.057 to 1.117) while mild-to-moderate drinkers showed a decreased risk of dementia (aHR, 0.844; 95% CI, 0.871 to 0.898). In subjects diagnosed with depression, heavy drinking increased the risk of dementia while mid-to-moderate drinking decreased the risk of dementia, highlighting the need for limiting alcohol consumption in depression patients in clinical settings.</p>