The SSAGA cohort is the amalgamation of the AL1 and AC cohorts. Adding these 2 cohorts should have given 4014 pairs however there was an overlap of 132 pair leaving a final sample of 3882 pair.

The SSAGA (Semi-Structured Assessment for the Genetics of Alcoholism) is an instrument designed to assess physical, psychological and social manifestations of alcoholism and related disorders. It is a semi-structured interview which capitalises on prior research in psychiatric epidemiology. As such, it relies heavily on items previously validated by other research interviews, including DIS, CIDI, HELPER, SAM, SADS, and SCID. The members of the COGA Assessment Committee are indebted to the many researchers who developed the interviews upon which, in part, the SSAGA is based.

The version of the SSAGA instrument used in the SSAGA 1 study is known as the Mini-SSAGA-OZ. It contains questions about:

• Family
• Use of alcohol
• Family use of alcohol
• Use of medications and drugs
• Depression