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 atte mpting to reduce the heterogeneity of expression of this complex disorder t o better understand its natural history and etiology. However, few typologi es 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 importa nt to their validity and utility. We test whether the mild, severe, and dys social typology distinguished cases of alcohol dependence with high familia l liability from those with low familial liability to alcoholism. Methods: Data came from the National Longitudinal Alcohol Epidemiologic Sur vey-1992, a household probability sample representative of those 18 years o f age and older in the contiguous US Response rate was 92%. Only whites wer e included here because the typology under study has been successfully appl ied 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 biologic al relative as alcoholic was based on the proband's report. All analyses we re weighted to adjust for sampling under a multistage stratified design. Results: Familial density of alcoholism (number of alcoholics/number of adu lt family members) substantially differed by proband alcohol dependence sta tus for both men and women (male probands-nonalcoholics 7%, mild 13%, sever e 25%, dyssocial 19%; female probands-nonalcoholics 8%, mild 18%, severe 33 %, dyssocial 24%;p < .001). Cross-fostering analysis of the probands with a doptive/stepparents indicated little difference between nonalcoholic and mi ld 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 ty pology as distinguishing subtypes with differing degrees of familial liabil ity to alcoholism. The typology may be useful when employing an extreme com parison strategy in genetic studies of alcohol dependence.