The sample comprised 2170 adolescents and young adults (1060 males and 1110 females) from the Prospective Study of the Collaborative Study on the Genetics of Alcoholism (COGA), examined within the age range of 12 to 25 years. COGA is a multisite collaboration designed to study the genetics of alcoholism (Begleiter et al., 1995) that has investigated members from multiplex alcoholic families (recruited through a proband in treatment) and a set of community (comparison) families, ascertained to be representative of the general population. These families were recruited during the years 1990 to 2000. The Prospective Study began in 2004 as a continuing study of adolescents and young adults from pedigrees ascertained in previous phases of COGA, and contained members from both the multiplex alcoholic families and the community (comparison) families. These families were recruited during the years 1990 to 2000. Over 80% of the subjects are from families originally recruited through an alcoholic proband, but fewer than 25% of the sample are first degree relatives of the probands, and many of the subjects from alcoholic families are only distantly related to the probands.
