Only individuals who reported drinking once per month for 6 months or more (regular drinking) at any evaluation were included in the analysis. If an individual was interviewed more than once, data from the SSAGA interview with the maximum total number of endorsed DSMIV alcohol dependence criteria was utilized. Age at onset of DSM-IV alcohol dependence (defined as age when full criteria were met), age at last interview, year of birth, gender and principal component 1 (PC1) for ancestry was included in the analysis. Table 1 shows the distribution of age at interview and age at onset of AD for the controls and cases respectively.
