Major NIH Study Will Examine the Effects of Drugs on the Developing Brain

The landscape of substance use among the nation’s youth is changing. Increasing public acceptance and shifting policies around marijuana are making that drug more accessible in some states. New designer drugs are appearing almost monthly. And e-cigarettes are changing the way young users become exposed to nicotine and even re-glamorizing what had until recently been a drug in decline. In this context, addiction professionals, not to mention parents and policymakers, want solid answers to these questions:

• How does occasional or regular use of marijuana, alcohol, nicotine and other substances—alone or in combination—affect the developing brains of teenagers?
• What neurodevelopmental pathways link adolescent substance use and pre-existing or emerging mental illnesses?
• How exactly does adolescent substance use affect cognition, motivation, social development, academic achievement, and other determinants of health, success, and well-being?

The Adolescent Brain Cognitive Development (ABCD) Study, headed by an NIH partnership that includes the National Institute on Drug Abuse, the National Institute on Alcohol Abuse and Alcoholism, the National Cancer Institute, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and others aims to answer these questions (and hopefully many more) over the next decade.

This nationwide longitudinal study will track approximately 10,000 individuals from around age 9 or 10 until young adulthood, not only collecting mental health, genetic, and behavioral data on substance use, school achievement, IQ, and cognition, but also, crucially, bring the latest neuroimaging to bear. The range of imaging and genetic tools now at our disposal offers unprecedented ways to chart the brain changes associated with substance use and to illuminate the causal mechanisms involved.

No large prospective study of the effects of drugs on neurodevelopment has ever followed participants from childhood all the way through this crucial second decade of active brain maturation. It will enable us to fill in some major gaps in our understanding. 

For example, while mounting evidence suggests that heavy marijuana use during this period can have profound adverse effects including lasting IQ loss and increased risk of mental illness in some individuals, even the best extant studies have suffered from methodological limitations as well as possible confounds like use of other substances, preexisting mental health comorbidities, and socioeconomic disparities. The scale of the ABCD study will give it the statistical power and measures to study in detail a wide range of adolescent drug-use trajectories, helping us sort out the individual effects of different drugs, interactive effects of multiple substances, and effects of initiation at different ages (compared to no initiation). By recruiting participants in childhood, we can establish the state of the brain prior to drug use and clarify the role of mental illness and the strength of genetic and socioeconomic risk factors. 

Due to its size and the technologies needed, the ABCD study will be costly, but the payoff could be enormous. Clarifying the neurodevelopmental impact of drugs, alcohol, and nicotine as well as the full range of behavioral antecedents and outcomes of substance use will inform public health and prevention efforts and thus benefit many future generations of young Americans. 

To learn more about the ABCD study, please visit: http://addictionresearch.nih.gov/adolescent-brain-cognitive-development-study