A new nationwide study will follow thousands of children for 10 years, starting in elementary school, in an attempt to answer questions about the risks and protective factors for adolescent substance use on the developing brain. The Adolescent Brain Cognitive Development (ABCD) Study will track exposure to substances (including nicotine, alcohol and marijuana), academic achievement, cognitive skills, mental health, brain structure and function, and many other variables.

By starting with youth before adolescence, the scientists will be able to assess the effects of the age of different experiences (trauma, poor nutrition, substance use) on brain development.

The study, funded by the National Institutes of Health, will begin with 11,500 children ages 9 and 10, before they start substance use, at 19 sites around the country. Recruitment for the trial is scheduled to launch in September.

The researchers hope to end up with 10,000 participants at the end of the study, says Sandra A. Brown, PhD, of the University of California, San Diego, who is co-principal investigator of the ABCD Coordinating Center, along with Terry L. Jernigan, PhD. Both children and their parents will be interviewed, and children will submit biological samples (such as saliva and hair samples), as well as undergo cognitive tasks and imaging tests such as MRIs.

The children will be representative of the nation in terms of gender, socioeconomic status, cultural background and rural versus urban location. They will be recruited through public, private and charter schools. Parents will answer questionnaires related to their child’s medical history, family medical history, mental health history and their own mental health and behavior.

“The advantage of having a large, national sample is that we’ll be able to identify what types of substances are the most impactful and deleterious,” Dr. Brown said. “We have set it up so scientists from around the world will have ready access to the data we collect each year, and they won’t have to wait five to 10 years until the study is done.”

“The biggest benefit of this study is its prospective nature – most of the kids won’t have used any substances when we start,” says Gaya Dowling, PhD, Director of the Adolescent Brain and Cognitive Development Project at the National Institute on Drug Abuse. “As they go through this risky period for substance use, we will be able to answer fundamental questions we haven’t been able to answer until now.”

Previous studies have compared young people who used substances with those who did not. “There was no way to know what their brains looked like before they started to use,” Dr. Dowling said. “This study has the potential to identify brain differences that may make some people more vulnerable to drug use.”

She notes that the study will cover much more than substance use—“although that is a critical component,” Dr. Dowling says. “We will be looking at everything from sports participation, to sleep, to cultural and environmental factors to get a complete picture about how various childhood experiences affect brain, social, emotional and academic development.”

The findings should have broad implications for prevention, Dr. Dowling added. “We hope we can come out with actionable information that can be used by educators, policy makers, doctors and parents to prevent substance abuse.”

“We want to understand what helps children work their way out of problems of substance abuse, in terms of environment, genetics, and social and cognitive abilities,” Dr. Brown said. “We will see how the brain improves, and how lives improve as young people stop using substances. That will guide us in terms of what we can expect.”

The study will look at the impact of occasional versus regular use of marijuana, alcohol, prescription drugs, tobacco (including e-cigarettes) and other substances, alone or in combination, on the structure and function of the developing brain. “We’ll be able to see whether different combinations of substances have a more profound impact on brain development than others,” she said.

It will also examine how the use of specific substances impacts the risk for using other substances, and what the brain pathways are that link teen substance use and risk for mental illnesses. The researchers will look at changes in substance use over the course of the 10 years of the study, and will examine new types of substance use, as well as new ways to abuse existing substances. They will also study how changing laws impact either the onset of substance use or prevalence of use.

The large amount of data will allow researchers to develop a more personalized approach to substance use prevention, Dr. Brown says. “We’ll be better able to understand potential protective factors each person has, and track trajectories of individual brain development. With that information, we can see the most helpful protective and resiliency factors for the individual, and make more refined recommendations for prevention.”