Among lifestyle-related factors, low to moderate alcohol drinking has been proposed as a protective factor against the development of age-related changes in cognitive function, predementia syndromes, and cognitive decline of degenerative (Alzheimer's disease, AD) or vascular origin (vascular dementia, VaD) in several longitudinal studies, but contrasting findings also exist. Furthermore, many of these studies were limited by cross-sectional design, restriction by age or sex, or incomplete ascertainment. Different outcomes, beverages, drinking patterns, or follow-up periods, or possible interactions with other lifestyle-related (i.e., smoking) or genetic factors [i.e., apolipoprotein E (APOE) genotyping] may be sources of great variability. Light to moderate alcohol use may be associated with a reduced risk of unspecified incident dementia and AD, while for VaD, cognitive decline, and predementia syndromes, the current evidence is only suggestive of a protective effect. In conclusion, as intervention studies are not feasible in this area, the best evidence comes from an overview of epidemiological studies, suggesting that the protective effects are more likely with wine consumption and the absence of an APOE e4 allele. At present, there is no indication that light to moderate alcohol drinking would be harmful to cognition and dementia, and it is not possible to define a specific beneficial level of alcohol intake.