proportion of overlap in the genetic factors that influence alcohol dependence and measures of AC during the heaviest period of drinking. Our analyses also suggest considerable overlap of genetic influences across different indices of current drinking and different measures of alcohol problems, across both samples, as evidenced by genetic correlations ranging from 0.45 to 0.99. Across both samples, frequency of intoxication and quantity of alcohol use were more strongly genetically correlated with alcohol problems than frequency of use. The Kendler and colleagues’ (2010) study of lifetime indices of consumption also found that drinking frequency had the lowest shared genetic overlap with alcohol problems. The Grant and colleagues’ (2009) study only evaluated a composite consumption factor score, making it impossible to evaluate differential informativeness of various drinking indices. However, the available data from this study and the Kendler study suggest that quantity of AC and frequency of heavy drinking or intoxication have greater shared genetic overlap with alcohol problem measures than measures of the frequency of alcohol use, which likely reflects a number social factors as well. Overall, genetic correlations were higher in the VATSPSUD sample, which may reflect the somewhat older mean age of the sample (36 vs. 24 years
