The sample comprised 2170 adolescents and young adults from the Prospective Study of the Collaborative Study on the Genetics of Alcoholism (COGA), a multisite collaboration designed to study the genetics of alcoholism (Begleiter et al., 1995), examined within the age range of 12 to 25 years. The Prospective Study began in 2004 as a prospective study of adolescents and young adults from pedigrees ascertained in previous phases of COGA, which contained members from alcoholic families (recruited through a proband in treatment) and a set of community (comparison) families, randomly ascertained to be representative of the general population. These families were recruited during the years 1990 to 2000. Although over 80% of the subjects are from families originally recruited through an alcoholic proband, fewer than 25% of the sample are first degree relatives of the probands, and many are only distantly related to the probands.
