In January, the National Institutes of Health (NIH) released the first complete baseline data set from the largest-ever study of adolescent health and development. The Adolescent Brain Cognitive Development (ABCD) Study will follow 11,874 children, starting at ages 9 and 10, for the next decade.
The ABCD Study will collect mountains of data: on neurological development, sociocultural and psychological factors, mental and physical health, environmental exposures, substance use, academic achievement and more. It's a huge undertaking, with huge implications for understanding children's development as they move through adolescence and into early adulthood.
"This is a massive effort, notable for both its scope and its depth," says Sandra Brown, PhD, vice chancellor for research and professor of psychology and psychiatry at the University of California, San Diego, and co-director of the ABCD Coordinating Center.
Because the project looks at so many different aspects of development, researchers will be able to mine the data to understand problems such as substance use and the emergence of mental illness, as well as the normal course of healthy adolescent development, adds Sara Jo Nixon, PhD, a professor of psychology at the University of Florida and a principal investigator of the study. "Often, we're interested in what went wrong, and indeed we'll have data to speak to those problems. But we'll also have data to look at resiliency and the kinds of factors—whether biological, psychological, social or cultural—that really nurture healthy development," she says. "This study is the epitome of what any psychological scientist would love to do."
ABCD basics
Launched in 2016, the ABCD Study is coordinated by the National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism, with support from numerous other NIH institutes and offices as well as the Centers for Disease Control and Prevention. To assist in recruitment, APA provided NIH with a statement encouraging families to consider participating, and an APA staff member serves on the ABCD national liaison board.
The study encompasses 21 research sites across the country and will follow participants for 10 years. It's an interdisciplinary effort, but psychologists Brown and Terry Jernigan, PhD, also at the University of California, San Diego, sit at the helm of the Coordinating Center, and 26 of the 40 principal investigators are psychologists. The study was carefully planned from the start to include a diverse group of adolescents, Brown says.
"We worked with high-quality epidemiologists, so the sample we're bringing to the table is a good reflection of the sociodemographics of the United States," she says.
To manage such a large project, the study's designers included funding for a coordinating center and a data management center. There's also a retention committee that works to ensure that as many of the participants as possible stick it out over the next decade—no small feat, considering the time investment. The project involves neuroimaging, genetic testing and behavioral testing as well as numerous questionnaires for the children, their parents and teachers. Participants will wear sensors 'round-the-clock for several weeks, most likely once a year, to collect data about activity levels, heart rate and sleep patterns. Investigators will even collect hair samples and baby teeth to study exposures to environmental toxins. The study includes more than 2,000 twins and triplets, allowing researchers to begin to tease apart genetic susceptibility from environmental influences.
As the children move into their teenage years, researchers will be able to explore questions about substance use, physical activity, sports injuries, sleep, learning and the emergence of mental health problems—and that's just for starters, says psychologist Susan Tapert, PhD, a professor at the University of California, San Diego, and an associate director of the ABCD Coordinating Center. "There's really an infinite number of questions that can be addressed here."
Principal investigators aren't the only scientists who will be able to answer them. The study was developed with an open-access model, and the data collected are freely available to any qualified researcher who wants to tap into them via the National Institute of Mental Health Data Archiveopens in new window.
The open-science philosophy will drive the science forward faster, while the large sample size and methodologically rigorous study design will ensure that the data are trustworthy, says Raul Gonzalez, PhD, an ABCD principal investigator and professor of psychology at Florida International University. "There is a replication crisis in the sciences, and a lot of that crisis is partially due to small sample sizes and a bias to publish significant results," he says. "With this study, there is an opportunity to assess a lot of questions that are controversial in our field."
Another unique element of the open-access model: Lead investigators won't have preferential access to data before they've been made available to the general public. Whether you're a principal investigator at one of the study sites or a grad student far from the action, you will have the same opportunity to access the same information at the same time through planned data releases. "That says a lot about the commitment of the leadership team to make sure transparency and reproducibility are addressed head-on," says Nixon.
Early findings
Investigators finished recruiting participants only last year, yet they have already begun drawing insights from the study. In one analysis of the baseline data, Aaron Blashill, PhD, and Jerel Calzo, PhD, of San Diego State University, explored differences in mood disorders and suicidality between 9- and 10-year-olds who identified as gay, lesbian or bisexual and those who identified as heterosexual. The rate of mood disorders was 22.5 percent for sexual minority children, compared with 6.9 percent for heterosexual children. Similarly, 19.1 percent of sexual minority children experienced suicidal thoughts, while just 4.6 percent of heterosexual children did (Journal of Affective Disordersopens in new window, Vol. 246, No. 1, 2019).
Other groups have pulled from ABCD data to explore a pressing 21st-century problem: the effects of screen time. Jeremy Walsh, PhD, now at the University of British Columbia Okanagan, and colleagues explored physical activity, screen-time behavior and sleep among more than 4,500 of the participants. They found that children who met recommended guidelines for these activities—at least 60 minutes of physical activity, no more than two hours of recreational screen time and 9 to 11 hours of sleep daily—had better cognition than those who did not, as measured by tests of attention, language abilities, episodic memory, working memory, executive function and processing speed. Unfortunately, though, only half of the children in the sample got the recommended amount of sleep, just 36 percent had fewer than two hours of screen time and a mere 17 percent engaged in the recommended amount of daily exercise, the researchers found (The Lancet Child & Adolescent Healthopens in new window, Vol. 2, No. 11, 2018).
Meanwhile, Tapert and colleagues found a link between screen time and a variety of complex structural brain changes, including cortical thickness, sulcal depth and gray matter volume. Different patterns of structural changes were related to downstream outcomes such as externalizing psychopathology and fluid and crystallized intelligence. But the changes differed depending on the type of screen media—and they weren't all bad (or all good) (Neuroimageopens in new window, Vol. 185, No. 1, 2019). "Kids who frequently played video games tended to have poorer mental health profiles and more family conflict, for example, while kids who were engaged in social media tended to have slightly better social and mental health functioning," she says. "It's not just how much screen time a child gets, but what they're doing."
With a single time point of data, it's too soon to make conclusions about the pros and cons of different screen media activities, Tapert notes. But as researchers follow the children in the years to come, they hope to be able to paint a more detailed picture of the effects of screen time on the brain.
A study that evolves
A lot can change in a decade. New social media platforms pop up almost overnight. Drug laws change, and the popularity of certain substances of abuse can wax and wane. New genetic tests and biomarkers may be discovered, new sensor technology could become available and neuroimaging techniques will be refined. The ABCD investigators have designed the study to accommodate such changes, so that new survey questions can be added and new technologies can be incorporated in future waves of data collection. "We have structures within ABCD that allow us to maintain enough continuity, so we can look at change in a systematic way and also augment the study using new methodologies," Brown says.
With its breadth, depth and flexible experimental design, the ABCD Study will serve as a model for other large-scale, long-term projects, investigators say. It also serves to showcase just how much psychology can do. "This is truly team science, led in large part by psychologists," Nixon says. "It speaks to the strength of our science, and the opportunity for psychologists to play a leading role in interdisciplinary research."
