2017 Children’s Mental Health Report
Substance Abuse Risks in Adolescence
Because their brain architecture is still not fully developed, adolescents’ brains are more susceptible to being radically changed by drug use — often specifically by impeding the development of the very circuits that enable adults to say “later” or “not at all” to dangerous or unhealthy options.
The same changes going on in the brain that allow adolescents to learn and thrive are also thought to make it more susceptible to lifelong damage than at other times. Early and sustained exposure to drugs and alcohol can more quickly lead to dependence than drug and alcohol use in adulthood, and is also linked to the development of mental health disorders like psychosis.¹
Of high school seniors in the U.S.⁴:
- 35.6% have used marijuana or hashish in the past year
- 14.3% have used an illicit drug other than marijuana in the past year
- 55.6% have used alcohol in the past year
- 12% have illicitly used a prescription drug in the past year
- 6.7% have used amphetamines in the past year
56% of those seen in treatment for cannabis abuse/dependence began using by 14 years of age, and 92% began by 18 years of age.⁵
Studies show there is heightened risk of eventually developing symptoms of drug dependence when drug use starts before age 18.⁶
- 3x risk with marijuana
- 2x risk with benzodiazepines (e.g., Ativan, Valium, etc.)
- 5x risk for cocaine, stimulants, and opioids
Marijuana and Psychosis
- Use of cannabis is linked to earlier onset of psychosis in teens and young adults already at risk⁷
- Daily use of marijuana doubles risk of onset of a psychotic disorder
Marijuana and cognitive function
- Persistent marijuana use is tied to declines in IQ which cannot be reversed even if use stops,⁸ a phenomenon that is exaggerated in adolescents who begin chronic use of marijuana before age 18
 Squeglia, L., Jacobus, J., & Tapert, S. (2009). The Influence of Substance Use on Adolescent Brain Development. Clinical EEG and Neuroscience, 40(1), 31-38. doi:10.1177/155005940904000110
 Hammond (2014).
 Ernst, M., Pine, D.S., & Hardin, M. (2006). Triadic model of the neurobiology of motivated behavior in adolescence. Psychological Medicine, 36(3): 299–312. doi: 10.1017/S0033291705005891
 Johnston (2016).
 Substance Abuse and Mental Health Services Administration (2007). Treatment Episode Data Set (TEDS) 1995-2005: National admissions to substance abuse treatment services. Rockville, MD: Author.
 Chen, C.-Y., Storr, C. L., & Anthony, J. C. (2009). Early-onset drug use and risk for drug dependence problems. Addictive Behaviors, 34(3), 319–322. doi:10.1016/j.addbeh.2008.10.021
 Kelley, E.A. (2016). Marijuana use in the immediate 5-year premorbid period is associated with increased risk of onset of schizophrenia. Schizophrenia Research, 171(1-3), 62-7. doi: 10.1016/j.schres.2016.01.015.
 Meier, M. H., Caspi, A., Ambler, A., Harrington, H., Houts, R., Keefe, R. S. E., … Moffitt, T. E. (2012). Persistent cannabis users show neuropsychological decline from childhood to midlife. Proceedings of the National Academy of Sciences, 109(40), E2657–E2664. doi:10.1073/pnas.1206820109