GENETIC AND ENVIRONMENTAL CONTRIBUTIONS TO ALCOHOL DEPENDENCE RISK INA NATIONAL TWIN SAMPLE - CONSISTENCY OF FINDINGS IN WOMEN AND MEN

Background. Genetic influences on alcoholism risk are well-documented in men, but uncertain in women. We tested for gender differences in ge netic influences on, and risk-factors for, DSM-III-R alcohol dependenc e (AD). Method. Diagnostic follow-up interviews were conducted in 1992 -3 by telephone with twins from an Australian twin panel first surveye d in 1980-82 (N = 5889 respondents). Data were analysed using logistic regression models. Results. Significantly higher twin pair concordanc es 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 o f well-educated respondents, and for selective attrition. AD risk was increased in younger birth cohorts, in Catholic males or women reporti ng no religious affiliation, in those reporting a history of conduct d isorder or major depression and in those with high Neuroticism, Social Nonconformity, Toughmindedness, Novelty-Seeking or (in women only) Ex traversion scores; and decreased in 'Other Protestants', weekly church attenders, and university-educated males. Controlling for these varia bles, however, did not remove the significant association with having an alcoholic MZ co-twin, implying that much of the genetic influence o n AD risk remained unexplained. No significant gender difference in th e genetic variance in AD was found (64% heritability, 95% confidence i nterval 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 sa me personality, sociodemographic and axis I correlates of alcoholism r isk are observed in women and men.