Our society is hotly debating the question of whether to decriminalize or even legalize the use of marijuana, and even though pro-legalization voices do not advocate making the drug legal for minors, it is likely that adolescents in more and more states will have easier access to this drug in coming years. At the same time, we are seeing new designer drugs being used by youth, and new ways of ingesting nicotine—in e-cigarettes—whose health effects are still barely understood. Consequently, more and more policymakers, physicians, parents, and teens are asking for definitive answers to decades-old questions about the risks and long-term effects of these various substances on health and well-being.
We have evidence (from both animal and human studies) that exposure to marijuana, alcohol, tobacco, and other drugs can affect the adolescent brain, possibly in a lasting way. But there are many gaps in our knowledge, and no large prospective study has yet been conducted that has followed participants all the way from childhood—i.e., before the first use of substances—through to adulthood, employing neuroimaging tools to assess the effects of substance exposure on brain development while measuring a broad range of behavioral antecedents and outcomes. The good news is, with the combined resources and ingenuity of multiple NIH institutes and other partners, we now have the capability to conduct such a study—one that would help us more confidently establish the effects of occasional or regular use of alcohol, tobacco, and other drugs on the brains and lives of young Americans.
We, the directors of NIDA, NIAAA, NCI’s Division of Cancer Control and Population Sciences, and NICHD, are now calling on the research community to help us design a large longitudinal study that would accomplish this objective. At the end of this month (May 27-28), there will be an expert panel workshop that is open to the public, to develop recommendations on best large-scale designs and measures to assess developmental effects of substance exposure; this will be followed this summer by a formal request for information (RFI) to get input from the research community on proposed study design and measures. We also intend to present a revised design for the study, based on input from the RFI, at a satellite symposium at the annual Society for Neuroscience meeting in November, in Washington DC.
We envision that this National Longitudinal Study of Neurodevelopmental Consequences of Substance Use will require tracking a large cohort of young people (approximately 10,000 individuals) for a decade, beginning in late childhood, and collecting mental health, genetic, and behavioral data on substance use, school achievement, IQ, and cognition, and crucially, using brain imaging. The array of neuroimaging and genetic tools now available enables us to study the nature of the brain changes that arise from substance use and shed light on causal mechanisms, to a degree never before possible. Among its many goals, the study should illuminate interactions between substances, identify neurodevelopmental pathways that link drug abuse with mental illnesses, and disentangle the effects of individual substances as well as characterize their combined effects.
This study will have the statistical power and the measures to study in detail a wide range of substance use trajectories; and because it will start before participants have begun using substances (i.e., around age 10), it should help allay doubts about certain confounding factors such as the state of the brain prior to drug use. It will advance the science of substance use in unprecedented ways, help direct prevention efforts, as well as inform policy makers.
A study of this magnitude and scope will be costly, but understanding the impact of drugs, alcohol, and tobacco on the developing brain has enormous potential to affect the health of current and future generations of young people. Fortunately, we are now in a position to provide confident answers to these research questions based on the most robust modern science.
To learn more about the National Longitudinal Study of Neurodevelopmental Consequences of Substance Use, including the meeting later this month to develop study recommendations, please visit: http://addictionresearch.nih.gov/cran-initiative-neurodevelopmental-consequences-substance-use
By Nora Volkow (Director, NIDA), George Koob (Director, NIAAA), Alan Guttmacher (Director, NICHD), and Bob Croyle (Director, Divison of Cancer Control and Population Sciences, NCI)