BACKGROUND: Consumers of light-to-moderate amounts of alcohol have a lower risk of dementia and, possibly, Alzheimer disease than do abstainers. Because vascular disease may contribute to symptoms of Alzheimer disease, reduction of cerebrovascular disease in consumers of light amounts of alcohol could account for that observation. However, a low concentration of alcohol may also have direct effects on the hippocampus, a brain structure highly affected by Alzheimer disease. OBJECTIVE: We investigated alcohol intake in relation to brain magnetic resonance imaging (MRI) findings of presumed vascular origin (ie, white matter lesions and infarcts) and findings more specifically found in early Alzheimer disease (ie, hippocampal and amygdalar atrophy). DESIGN: In a population-based sample of 1074 older persons without dementia (aged 60-90 y), we made brain MRIs from which we rated white matter lesions and brain infarcts. In a subset of 509 people, hippocampal and amygdalar volumes on MRI were measured. Alcohol intake was assessed by using a structured questionnaire. We categorized alcohol intake as lifetime abstention and very light (<1 drink/wk), light (>/=1 drink/wk to <1 drink/d), moderate (>/=1 drink/d to <4 drinks/d), and heavy (>/=4 drinks/d) intakes. RESULTS: Persons whose alcohol consumption was light to moderate had less severe white matter lesions and brain infarcts on MRI than did abstainers or heavy drinkers. Abstainers and very light drinkers had smaller hippocampal and amygdalar volumes on MRI than did light-to-moderate drinkers, but only if the former carried an apolipoprotein (APOE) epsilon4 allele. CONCLUSION: Light-to-moderate alcohol intake is associated with a lower prevalence of vascular brain findings and, in APOE epsilon4 carriers, hippocampal and amygdalar atrophy on MRI.