The data are from the Prospective Study of the Collaborative Study on the Genetics of Alcoholism (COGA). The COGA study, which began in 1989 to identify the vulnerability and protective genes for alcoholism, has been described elsewhere (Begleiter et al 1995; Reich et al 1998; Nurnberger et al 2004); only a brief overview is provided here. High risk families were ascertained through probands in inpatient or outpatient treatment for alcoholism at 7 sites across the United States, with all first degree relatives who were aged 7 or older interviewed with a comprehensive, highly reliable and valid assessment (Bucholz et al. 1994; Hesselbrock et al. 1999). In families with at least 2 affected first degree relatives of the proband, recruitment was extended to additional relatives with an expanded protocol that included neuropsychological and neurophysiological evaluations and collection of blood for DNA. Comparison families, drawn from various sources (e.g., dental clinics, drivers’ registries), were studied with the same protocol.
