Familial transmission of alcoholism among nonalcoholics and mild, severe, and dyssocial subtypes of alcoholism

BACKGROUND: In the field of alcohol studies, there are many typologies attempting to reduce the heterogeneity of expression of this complex disorder to better understand its natural history and etiology. However, few typologies have included empirical assessment of the degree of familial liability. To the extent there is variability in genetic vulnerability to alcoholism, inclusion of measures of this variability in proposed typologies is important to their validity and utility. We test whether the mild, severe, and dyssocial typology distinguished cases of alcohol dependence with high familial liability from those with low familial liability to alcoholism. METHODS: Data came from the National Longitudinal Alcohol Epidemiologic Survey-1992, a household probability sample representative of those 18 years of age and older in the contiguous US Response rate was 92%. Only whites were included here because the typology under study has been successfully applied to this race/ethnic group only. The total number of respondents were 32,447 and included 13,825 men and 18,622 women. Identification of a biological relative as alcoholic was based on the proband's report. All analyses were weighted to adjust for sampling under a multistage stratified design. RESULTS: Familial density of alcoholism (number of alcoholics/number of adult family members) substantially differed by proband alcohol dependence status for both men and women (male probands-nonalcoholics 7%, mild 13%, severe 25%, dyssocial 19%; female probands-nonalcoholics 8%, mild 18%, severe 33%, dyssocial 24%; p <.001). Cross-fostering analysis of the probands with adoptive/stepparents indicated little difference between nonalcoholic and mild alcoholic probands and suggests greater influence of biological parents for severe subtype probands compared to other probands. CONCLUSIONS: These results suggest construct validity for the alcoholism typology as distinguishing subtypes with differing degrees of familial liability to alcoholism. The typology may be useful when employing an extreme comparison strategy in genetic studies of alcohol dependence.