Genetic and environmental contributions to alcohol dependence risk in a national twin sample: consistency of findings in women and men

TLDR: In a follow-up interview with twins from an Australian twin panel first surveyed in 1980-82 (N=5889 respondents), data were analysed using logistic regression models and no significant gender difference in the genetic variance in AD was found as mentioned in this paper.

Abstract: Background. Genetic influences on alcoholism risk are well-documented in men, but uncertain in women. We tested for gender differences in genetic influences on, and risk-factors for, DSM-III-R alcohol dependence (AD).Method. Diagnostic follow-up interviews were conducted in 1992–3 by telephone with twins from an Australian twin panel first surveyed in 1980–82 (N=5889 respondents). Data were analysed using logistic regression models.Results. Significantly higher twin pair concordances were observed in MZ compared to DZ same-sex twin pairs in women and men, even when data were weighted to adjust for over-representation of well-educated respondents, and for selective attrition. AD risk was increased in younger birth cohorts, in Catholic males or women reporting no religious affiliation, in those reporting a history of conduct disorder or major depression and in those with high Neuroticism, Social Non-conformity, Toughmindedness, Novelty-Seeking or (in women only) Extraversion scores; and decreased in ‘Other Protestants’, weekly church attenders, and university-educated males. Controlling for these variables, however, did not remove the significant association with having an alcoholic MZ co-twin, implying that much of the genetic influence on AD risk remained unexplained. No significant gender difference in the genetic variance in AD was found (64% heritability, 95% confidence interval 32–73%).Conclusions. Genetic risk-factors play as important a role in determining AD risk in women as in men. With the exception of certain sociocultural variables such as religious affiliation, the same personality, sociodemographic and axis I correlates of alcoholism risk are observed in women and men.