COGA ascertained probands in treatment for alcohol dependence, and a smaller number of comparison individuals from the same communities, and then recruited their families. Approximately 75% of the families were ascertained via a proband in treatment for alcohol dependence. Initial recruitment prioritized families with at least three first degree relatives meeting criteria for alcohol dependence (i.e., densely affected) although many families include more than three individuals with AUD, hence the higher than population prevalence of alcohol dependence and AUD (Table 1). As shown in Figure 2, the proportion of families where more than half of the members met criteria for AUD ranged from 51% to 57%. Both probands and family members were characterized with age‐appropriate assessments, including a standardized diagnostic instrument designed by COGA, the Semi‐Structured Assessment for the Genetics of Alcoholism (SSAGA), 10 , 11 administered by trained interviewers. Additional questionnaires (e.g., personality, family history and home environment) were also administered (see 2. Sample and Clinical Data for details). Given the focus on brain‐related phenotypes, COGA collected neurocognitive and neurophysiological measures using EEG and ERP/EROs (Event‐Related Potentials/Event‐Related Oscillations; see
