Genetic and environmental influences on lifetime alcohol-related problems in a volunteer sample of older twins.

Few studies have employed genetically informative designs to study the causes of alcohol-related problems in nonclinical populations. We report patterns of alcohol abuse in a community-based 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-related problems, with higher prevalence among males and lower frequency among older birth cohorts. Significant associations were found between severity of alcohol abuse (adapted from Feighner criteria) and age of drinking onset, parental history of alcohol problems and, among males, lower educational attainment. Model-fitting analyses based on data from 650 identical and 479 fraternal twin pairs indicate substantial family resemblance for a variety of definitions of lifetime alcohol abuse and alcohol problems. The median estimate of genetic variance across several definitions of alcohol problems was 38.5%, while that for shared environmental influence was 15.5%. Gender heterogeneity was not found for magnitude of genetic and environmental influences, but these comparisons were limited by low statistical power. Findings are discussed with reference to the literature on alcohol abuse among older adults and the genetic epidemiology of alcoholism.