A longitudinal study of risk factors for incident drug use in adults: findings from a representative sample of the US population.

<bold>Objective: </bold>To examine baseline mental disorders and other correlates among people who have not previously used drugs as potential risk factors for incident drug use at 3-years' follow-up.<bold>Method: </bold>Data came from the National Epidemiologic Survey on Alcohol and Related Conditions (commonly referred to as the NESARC) Wave 2 (2004 to 2005; n = 34 653), a longitudinal nationally representative survey of mental illness in community-dwelling adults. The study group consisted of people who reported no history of any illicit drug use or prescription drug misuse at Wave 1 (2001 to 2002). Logistic regression analyses were used to compare people with first-episode drug use at Wave 2 (n = 1145) to those who remained abstinent (n = 25 790) across various Wave 1 correlates, including sociodemographic factors, mental disorders (including alcohol use disorders and nicotine dependence), childhood adversity, and family history of substance use disorders.<bold>Results: </bold>All measures of childhood adversity were associated with an increased risk of incident drug use, as were alcohol or drug problems in first-degree relatives. In models adjusted for childhood adversity and a family history of addiction, a pre-existing mood disorder (AOR 1.31; 95% CI 1.04 to 1.64), personality disorder (AOR 1.82; 95% CI 1.50 to 2.20), previous nicotine dependence (AOR 1.41; 95% CI 1.09 to 1.83), and alcohol abuse or dependence (AOR 1.96; 95% CI 1.48 to 2.60) were independently associated with new-onset drug use at follow-up.<bold>Conclusions: </bold>Specific mental disorders independently increase the risk of progression to incident drug use among people who were previously abstinent. Early-life adversities and addiction in family members accounts for some, but not all, of this observed relation. [ABSTRACT FROM AUTHOR]