Information on alcohol use disorders (AUD) was obtained from three registers. The Danish Psychiatric Central Register contains data on all admissions to Danish psychiatric inpatient facilities. It has been computerized since April 1, 1969, and since 1995 outpatients have also been registered (Munk-Jorgensen & Mortensen, 1997). Parents and offspring were followed in the register until May 7, 2007. The Danish National Hospital Register was established in 1977 and included all admissions to somatic hospital departments in Denmark until 1994, when it was expanded to also include outpatient and emergency room contacts (Andersen et al., 1999). Parents and offspring were followed in the register until April 24, 2007. In both these registers diagnoses were classified according to the International Classification of Diseases, 8th Revision (ICD-8) until 1994, when the ICD-10 was introduced. The WINALCO-database (Becker, 2004) contains records of individuals treated for alcohol problems at an outpatient clinic covering the greater Copenhagen and Frederiksberg municipalities since 1954 (Becker, 2004). Parents and offspring were followed in the register until October 7, 2008.
