Marijuana Use and Later Problems: When Frequency of Recent Use Explains Age of Initiation Effects (and When It Does Not)

Abstract

Tobacco, alcohol, and marijuana are among the most commonly used drugs during adolescence. Initiation of marijuana use typically peaks at age 15, with risk of initiation continuing throughout adolescence. The goal of the current study was to prospectively examine the influence of age of marijuana initiation on four outcomes: physical health, mental health, illicit drug use other than marijuana, and marijuana-use related consequences at age 18. We controlled for several important predictors of adolescent drug use and its associated consequences, including demographics, social bonding variables, personality variables, and recent use of marijuana. Baseline survey data were collected in 1984 at grade 7 and follow up surveys were conducted at grades 8, 9, 10, and 12 (N = 2079). This initiates-only sample was 47% female, 66% White, 11% African American, 13% Hispanic, 5% Asian, and 5% other race or ethnicity. Findings indicated that age of initiation predicted marijuana consequences and other illicit drug use after controlling for demographic, social, and behavioral factors. However, once frequency of recent marijuana use was included in the models, age of initiation was only associated with other illicit drug use. Both primary and secondary prevention are needed to curb marijuana use and its associated harms.

Keywords:

• adolescent
• marijuana
• longitudinal
• initiation

Notes

¹Analyses were also run with treatment effects included. All results were consistent with current findings for all outcome variables.

Additional information

Notes on contributors

Phyllis L. Ellickson

Phyllis L. Ellickson, Ph.D., is Director of the Center for Research on Child and Adolescent Health, and a Senior Behavioral Scientist at RAND. She led the team that developed and evaluated Project ALERT, an exemplary prevention program that has been disseminated throughout the United States. She has also published extensively on the patterns and antecedents of adolescent drug use, violence and dropping out; racial/ethnic differences in drug use; and the challenges of conducting large-scale field trials and field experiments.

Elizabeth J. D'Amico

Elizabeth D'Amico, Ph.D., is an Associate Behavioral Scientist at RAND and a licensed clinical psychologist. Her research focuses on understanding the underlying mechanisms of adolescent and preadolescent risk-taking behavior and developing innovative psychosocial interventions for this diverse population.

Rebecca L. Collins

Rebecca L. Collins, Ph.D., is a Senior Behavioral Scientist at RAND whose recent research examines the determinants and consequences of health risk behavior. She currently leads a national longitudinal study exploring associations between television viewing and adolescent sexual attitudes and behavior, is a key investigator for another longitudinal study of the effects of alcohol advertising on adolescent drinking, and leads or co-leads two additional studies examining relationships between substance use and other high-risk behaviors. She has published extensively on adolescent risk and the health behavior, coping, and treatment-related attitudes of people with HIV.

David J. Klein

David J. Klein (M.S., Biometry, University of Southern California, 1996). David J. Klein is a Full Quantitative Analyst in RAND's Statistical Research and Consulting Group, performing data management and statistical analysis. He has worked on a wide variety of research projects at RAND, mostly in the health field. Among others, his current projects include studies on substance use, parent-child communications, quality and quantity of health care usage, and medical education.