Following the methods of Cohen et al. (2003), the actual calendar completed with the subjects contained columns for each year of the subject’s life. The first rows, completed early in the interview, documented key changes in living situation in addition to major educational, employment and interpersonal mile-stones. Toward the end of the interview, after completion of drug sections assessing standard questions about age at first use, maximal lifetime use and symptoms of abuse and dependence, we returned to the calendar. For alcohol, we asked subjects, starting with the age at which they reported using alcohol, the average number of times per month they consumed alcohol and the average number of drinks they consumed per day when drinking. We defined a drink as ‘one bottle of beer, one glass of wine or one shot of liquor’. We then moved forward in time year by year up to their present age, asking if their drinking patterns had changed and, if so, asked them to document the new pattern. If necessary, the interviewers would use other memory prompts from the information previously recorded
