For the present study we used the maximum value (best estimate of maximum level of alcoholic symptomatology capable of being achieved by the individual) from all waves of the percentage of alcohol dependence symptoms (tolerance, withdrawal, craving) and problems (legal and social complications) reported from a 31-item checklist, the MLS Drinking and Drug History 32 which contains a list of all symptoms listed in DSM-IV and others from earlier diagnostic systems 33 (See Supplementary materials). It incorporates non-overlapping items from the 1978 NIDA Survey 34, from the American Drinking Practices Survey35 and from the V.A. Medical Center (University of California, San Diego) Research Questionnaire for Alcoholics36. They provide data on quantity, frequency and variability of alcohol consumption, frequency of drug use, and multiple questions on symptoms, consequences and troubles related to the use of these substances and have been extensively used in a variety of national surveys and clinical settings 37. The modal value is zero. Alcohol dependence and abuse lifetime diagnosis was made by a trained clinician based on DSM–IV criteria at each wave using three instruments: Diagnostic Interview
