The cross‐sectional, family‐based data gathered early in COGA yielded a rich series of investigations exploring in‐depth characterizations of the AUD phenotype (subtypes, withdrawal, and time course), familial aggregation of substance use disorders, comorbidity with other substance dependences and with non‐substance disorders like depression, anxiety, eating disorders, and suicidality, to name a few. Among the array of published findings based on COGA data, we highlight several here in acknowledgement of their contributions to some key research questions. An analysis of the large array of alcohol problems collected in Wave 1 contributed to the nosological debate on dimensional versus categorical representations of substance use disorder, finding strong evidence in the full COGA sample that the disorder was best conceptualized on a severity dimension rather than by categories of specific symptoms. 23 Replicating results from a large Australian twin sample, 24 this finding has also been observed in numerous subsequent studies across general population, collegiate and treatment samples. 25 , 26 , 27 In another COGA study, analysis of the early family data led to observations of both common and specific evidence for
