Age of alcohol and marijuana use onset predicts weekly substance use and related psychosocial problems during young adulthood

The present study examined whether age of alcohol and marijuana use onset during adolescence predicted later substance use and related problems in several areas of psychosocial functioning among young adults. A total of 621 participants completed surveys regarding current substance use from 7th through 12th grades and also completed a survey as young adults (age 24) that included questions regarding the impact of alcohol and drug use on several areas of functioning. Findings indicated that earlier age of substance use onset was positively associated with weekly use of alcohol and marijuana during young adulthood, as well as substance-related occupational, relationship, and legal problems. The majority of young adults reporting problems due to alcohol or drug use had first reported alcohol and/or marijuana use before entering high school. For women, onset of substance use prior to high school was more strongly related to negative drug-related occupational outcomes than was concurrent weekly substance use as a young adult. Findings indicated that the negative effects of early onset substance use are strongest in social and occupational functioning, areas that correspond to the DSM criteria relevant to the diagnosis of alcohol or substance use disorder.