ABCD Study

The ABCD (Adolescent Brain Cognitive Development) Study is an ongoing longitudinal research study being undertaken by a consortium of 21 data collection sites across the United States. The study aims to collect data on the behavior and brain development of over 11,500 children beginning at age 9-10 and continuing through young adulthood. 
Motivation.
The ABCD Study is primarily motivated by the need to develop a "baseline" for adolescent brain development. A primary goal of the study is to characterize the development of youth before initiation of substance use, as well as "characteriz(ing) the impact of subctance exposure on adolescent neurocognitive development". Data are also collected on sleep habits, screen time, demographics, clinical measures, imaging, and biological samples to allow a holistic picture of adolescent development. 
Behavior.
Several behavioral tests and measures are administered, including measures of IQ, language, and working memory
Biospecimens.
Several different biospecimen samples are collected for the analysis of hormones, DNA, and neurotoxic substances. These biospecimens include hair, blood, saliva, and deciduous (baby) teeth. 
Deciduous teeth can be tested for environmental neurotoxins that were encountered at specific ages (even as early as prenatally) by analyzing the chemical content of successive tooth layers. The ABCD Study currently banks teeth provided by participants for future analyses. Examining toxic chemical exposure at various life stages is expected to provide insight into how exposure to substances like heavy metals affects brain and behavior development.
Imaging.
The ABCD imaging protocol includes 3D T1 and 3D T2-weighted scans, as well as diffusion weighted images, resting state scans, and three functional magnetic resonance imaging (fMRI) tasks. The fMRI tasks include: Monetary Incentive Delay task, Stop Signal task, and the EN-back task (for emotional regulation). Order and version are randomized across subjects, and when taken together the tasks are meant to measure reward processing, motivation, impulsivity, impulse control, working memory, and emotion regulation. 
Motion artifacts are a perpetual concern in MRI data acquisition, especially when collecting data from very young or elderly populations. To enhance the data collection during scanning sessions, new ABCD study participants go through a simulated MRI environment where they can receive real-time motion feedback in order to practice being in the scanner.
Impact of the COVID-19 Pandemic.
Due to physical distancing advisories connected with the ongoing COVID-19 pandemic, the study is being adapted to virtual assessments. At the moment it is unclear how profoundly this disturbance will affect the longitudinal arm of the study, and the disruption will likely vary by site. 