Alcohol initiation was defined as the first time the participant ever used alcohol with age of onset recorded as the age this first occurred. For those who endorsed ever using alcohol at more than one assessment, Cronbach alpha for age of first alcohol initiation was 0.78, indicating acceptable test-retest reliability across waves 1, 3, and 4. We chose the lowest third of the age at initiation distribution (age 15 or younger) to represent early use. First AUD symptom was coded positive for individuals who endorsed one or more symptoms of alcohol abuse or dependence with age at first AUD symptom derived from reported age(s) that each endorsed symptom was first experienced. A Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition [DSM-5;(Association, 2013)] AUD proxy was calculated by identifying individuals who endorsed two or more of the 10 symptoms – 7 dependence and 3 abuse (legal problems are excluded from DSM-5) within the same 12-month period at some point during their life [The symptom craving was not assessed; however, the psychometric benefit of adding craving to AUD is unclear (Hasin
