NIH has completed enrollment in its Adolescent Brain Cognitive Development (ABCD) Study, positioning it to release baseline data on nearly 12,000 children early next year.
The study is using functional magnetic resonance imaging (fMRI) to monitor how the brains of children develop as they go through adolescence.
By pairing the images with data on social, behavioral, physical and environmental factors, the NIH scientists aim to create a resource that they and other researchers can use to understand the elements that shape brain development and the prospects of young people.
In recent years, advances in neuroimaging have begun to reveal the changes to brain structure and function that occur during adolescence. These revelations added new layers to explorations of why people typically start using potentially addictive substances during this period, but left key questions about interactions between genetics, brain structure, drugs and long-term outcomes unanswered.
With technology facilitating the generation and dissemination of new types of data, researchers at the National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism set up the ABCD study to probe these questions. The potential for the data to answer questions outside of drug and alcohol abuse led eight other NIH institutes and offices, CDC and other federal groups to get involved.
Now, the collaborators have completed enrolling 11,874 nine to 10 year old children, including 2,100 twins and triplets, in the ABCD study. The milestone means baseline data on all the participants will be available early next year.
Images are the centerpiece of the resource created by the study. In designing the imaging piece of the study, the researchers built on the work of the Human Connectome Project and the Pediatric Imaging, Neurocognition, and Genetics Study.
The result is an MRI acquisition protocol that uses weighted images to measure brain structure, and resting state and task-based fMRI to measure brain function. NIH has designed the protocol to be compatible with the Siemens, General Electric and Phillips scanners installed at the 21 facilities that have enrolled participants.
As it stands, images from the scanners and data from other sources offer a snapshot of the children at a point in time. This information has some value but its full potential will only be realized when it is analyzed alongside data gathered later in the 10-year study. By tracking changes in the children over time, NIH hopes to identify factors associated with mental health risk and resilience, show how sleep and other health behaviors affect brain development and generate as-yet-unforeseen insights.
The release of the data will provide researchers with a major new repository to explore. When NIH released data on the first 4,500 participants earlier this year, the resource took up 30 terabytes of storage. For context, the Library of Congress print collections takes up 10 terabytes. Given the size of the database, NIH plans to make it available for analysis through an online portal, thereby freeing researchers from the need to download the repository.
Multiple barriers stand between NIH and the realization of those hopes. Retention is perhaps the most fundamental challenge. To gather meaningful data, the researchers need to keep participants engaged in the study and compliant with the annual schedule of face-to-face meetings over a 10 year period in which their lives will change dramatically. The big risk is that some groups of subjects, such as those of a certain gender or socioeconomic status, will be more likely to drop out than others.
To mitigate the risk that such non-random attrition will limit the generalizability of the data, the team is paying the children and their families at each assessment point and trying to make participation as positive as possible. The success of these efforts and the data generation program they support will become clear in the years to come.