Correlations among first-degree relatives for responses on the self-rating of the effects of alcohol questionnaire in teenagers

Objective: The level of response (LR) to alcohol is an intermediate phenotype related to the alcoholism risk, with a heritability of at least 0.4 as estimated from alcohol challenge experiments. A measure of LR that can be used in adolescence at a time close to the first drinking experience, and that is less expensive than alcohol challenge experiments, is the Self-Rating of the Effects of Alcohol (SRE) Questionnaire. This questionnaire contains questions related to the number of drinks required for up to four different effects early in the drinking career ("first five" score). The familial characteristics of SRE responses have been estimated in adults; however, no study has evaluated familial and potential genetic components of the first five SRE score in adolescents. This article presents data regarding the familial nature of SRE-based scores among a sample of teenagers. Method: As part of the Collaborative Study on the Genetics of Alcoholism Phase II (follow-up) Protocol, SRE scores were available on 251 females and 236 males ages 13-19 years. These analyses compare the correlations among father-offspring, mother-offspring, sibling pairs and comparable unrelated individuals. Results: For the 487 subjects, correlations among first-degree relatives ranged from 0.14 to 0.22 and were all significant. Correlations among comparable unrelated pairs ranged from 0.02 to 0.06 and were nonsignificant. When males and females were evaluated separately, the pattern of results, with higher correlations among first-degree relatives than among unrelated individuals, was similar, although, perhaps reflecting fewer subjects, correlations were more variable. Conclusions: Although not providing a definitive evaluation of heritability, the results are consistent with a potential proportion of the variance related to genes for first five SRE scores of between 0.3 and 0.4. These results parallel previously published data in adults and are similar to heritability estimates for LR on alcohol challenges. The data support the potential use of the first five SRE score in adolescents as a measure of LR in genetic and environmental model-based studies in young populations for whom the evaluation of LR is taking place at a time close to the onset of drinking.