Environmental and genetic influences on alcohol use in a volunteer sample of older twins.

A growing literature supports genetic contributions to familial resemblance for alcohol use characteristics, but few studies have focused on the mechanisms underlying alcohol use among older persons. We report patterns of alcohol use in a U.S. volunteer sample of 3,049 female and 1,070 male twins aged 50 to 96. Significant gender and age effects were found for self-report measures of current and lifetime alcohol use, with greater intake among males and current and lifetime abstinence more common among older participants. Comparisons with data obtained 4 years previously revealed high stability for quantity and frequency of alcohol consumption. Twin pairs with more frequent social contact tended to be more similar for lifetime and current alcohol use. Biometrical genetic modeling results indicate that use of alcohol is highly familial, with both genetic and shared environmental factors contributing to initiation of alcohol use among men and women. Among drinkers, however, the degree of twin resemblance for consumption behaviors is low to moderate and appears to be regulated by shared genes rather than shared environments. These data are consistent with a multidimensional process, suggesting that the determinants of whether one drinks in older age differ from those underlying how much or how often alcohol is consumed.