In a May 16 blog focused on the upcoming three-day meeting on the National Longitudinal Study of Neurodevelopmental Consequences of Substance Use later this month, the directors of four institutes at the National Institutes of Health wrote about the likelihood that more adolescents will have easier access to marijuana in coming years. New designer drugs and e-cigarettes, which provide a way to ingest nicotine (and have health effects that are “barely understood”), increase even more the need to answer questions about the risks of long-term effects of these substances, according to the blog.

So a huge study is going to be done.

The institutes envision tracking a cohort of about 10,000 young people for a decade, beginning in late childhood. They would collect mental health, genetic and behavioral data on substance use, school achievement, IQ and cognition. The study would use brain imaging, which the institutes say is crucial. “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,” they write. The study should “identify neurodevelopmental pathways that link drug abuse with mental illness, and disentangle the effects of individual substances as well as characterize their combined effects.”

The study will start around age 10, before participants have started using substances.

“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,” according to the blog. “Fortunately, we are now in a position to provide confident answers to these research questions based on the most robust modern science.”

The authors are Nora Volkow, M.D., director of the National Institute on Drug Abuse (NIDA); George Koob, Ph.D., director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA); Alan Guttmacher, M.D., director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD); and Bob Croyle, Ph.D., director of the Division of Cancer Control and Population Sciences at the National Cancer Institute (NCI).

There is evidence from animal and human studies that exposure to marijuana — and other drugs — can affect the adolescent brain, the blog notes. “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,” according to the blog.

That’s the purpose of the longitudinal study, which has not even been designed yet — to study what the effects are of “occasional or regular use of alcohol, tobacco, and other drugs on the brains and lives of young Americans.”

The research community is now being asked to help design a study that would do just this. An expert panel workshop on May 27–28, which is open to the public, will develop recommendations on designs and “measures to assess developmental effects of substance exposure.” After this meeting, there will be, sometime this summer, a formal request for information (RFI) for input from the research community on the proposed design and measures. There will be a revised design, based on RFI input, via a symposium at the annual Society for Neuroscience meeting in Washington, D.C., in November.

For more about the meeting, go to

The initiative is part of the CRAN (Collaborative Research on Addiction at NIH) that was announced last year (see ADAW, December 23, 2013).