Genetic and environmental contributions to alcohol dependence risk in a national twin sample: consistency of findings in women and men
A. C. HEATH a1 , K. K. BUCHOLZ a1 , P. A. F. MADDEN a1 , S. H. DINWIDDIE a1 , W. S. SLUTSKE a1 , L. J. BIERUT a1 , D. J. STATHAM a1 , M. P. DUNNE a1 , J. B. WHITFIELD a1 and N. G. MARTIN a1
a1 Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA; Queensland Institute of Medical Research and Queensland University of Technology, Brisbane, Queensland, Australia and Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
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.
Address for correspondence: Dr Andrew C. Heath, Department of Psychiatry, Washington University School of Medicine, 4940 Children's Place, St Louis, MO 63110, USA.