Substance use (46.6 – 80.3%), including early use (onset age≤14 years: 14.7 – 22.2%) was common by the most recent interview (Table 1). African-American participants were less likely to report early alcohol and nicotine use but more likely to report early cannabis use. Males were more likely to report early cannabis use. Combining data across the six assessments, 13.3%, 20.0% and 17.4% of the respondents met criteria for a lifetime history of alcohol, nicotine and cannabis dependence respectively. Correlations across the substance use measures ranged from 0.77 – 0.88 and from 0.61 – 0.67 across the substance dependence measures. SI was reported by 30.2% while SA was reported by 5.8% of respondents. Despite the items being non-nested, no one reported SA without also reporting SI. Both SI and SA had a median onset age of 15 years and were more commonly reported by females than males; SI was significantly less frequently reported by African-American participants, but no significant ethnic differences emerged for SA. Overall, SI and SA were considerably more common in those reporting early substance use (Supplemental Table S2),
