January 1991

Heterogeneity in the Inheritance of AlcoholismA Study of Male and Female Twins

Author Affiliations

From the Addiction Research Center, National Institute on Drug Abuse (Dr Pickens) and the Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University (Dr Svikis), Baltimore, Md; and the Departments of Psychology (Drs McGue and Lykken) and Psychiatry (Drs Lykken, Heston and Clayton), University of Minnesota, Minneapolis.

Arch Gen Psychiatry. 1991;48(1):19-28. doi:10.1001/archpsyc.1991.01810250021002

• Genetic influence on risk for alcoholism was examined in a US treatment sample of 50 monozygotic (MZ) and 64 dizygotic (DZ) male and 31 MZ and 24 DZ female same-sex twin pairs. For the DSM-IIIcomposite diagnosis of Alcohol Abuse and/or Dependence, statistically significant MZ/DZ differences in concordance were found with male, but not female, twins. For specific diagnoses, MZ/DZ differences were found in male subjects for both Alcohol Abuse and Alcohol Dependence, while MZ/DZ differences in female subjects were found only for Alcohol Dependence. The male MZ/DZ concordance difference for composite diagnosis but not for Alcohol Dependence could be accounted for statistically by differences in age of onset between MZ and DZ probands. As with alcohol, differences in MZ/DZ concordance were found for DSM-III composite diagnoses of Other Substance Abuse and/or Dependence with male, but not female, twins. Using Epidemiological Catchment Area data to estimate the population base rates of both alcohol and other substance use disorders allowed for heritability analyses that showed genetic factors to have only a modest influence on overall risk in both sexes (heritability estimates of approximately 0.35 for male subjects and O.24 for female subjects). However, evidence for heterogeneity in the pattern of inheritance was also found, suggesting forms of alcoholism that may be moderately to highly heritable.