Heritability of usual alcohol intoxication and hangover in male twins: the NAS-NRC Twin Registry.

BACKGROUND Alcohol consumption is influenced by heritable factors. The genetic influence on usual high-density drinking, including alcohol intoxication and hangover, is unknown. We aim to estimate the heritability of usual high-density drinking. METHODS A total of 13,511 male twins in this cross-sectional study were included from the National Academy of Sciences-National Research Council (NAS-NRC) Twin Registry. Data on the frequency of alcohol intoxication and alcohol hangover over the past year, that is, usual high-density drinking (phenotypes), were collected through a self-administered questionnaire when twins were middle-aged in 1972. Structural equation modeling was used to estimate the variance components of phenotypes. RESULTS The mean of the frequency of usual high-density drinking in the entire twin population was 0.16 times per month for intoxication and 0.18 times per month for hangover. The heritability of usual alcohol intoxication was 50.7% (95% confidence interval [CI] 46.2 to 55.0) before and 49.9% (95% CI 45.3 to 54.2) after the body mass index (BMI) adjustment. The heritability of usual hangover was 55.4% (95% CI 51.2 to 58.6) before and 54.8% (95% CI 50.6 to 58.8) after adjustment for BMI. Unshared environmental factors between co-twins explained the remaining variance in alcohol intoxication and in hangover. CONCLUSIONS Both genetic and unshared environmental factors have important influences on usual alcohol intoxication and hangover. These findings are important in understanding the occurrence of and developing interventions for usual high-density drinking.