Neurodevelopmental maturation takes place in a social environment in addition to a neurobiological one. Characterization of social environmental factors that influence this process is therefore an essential component in developing an accurate model of adolescent brain and neurocognitive development, as well as susceptibility to change with the use of marijuana and other drugs. The creation of the Culture and Environment (CE) measurement component of the ABCD protocol was guided by this understanding. Three areas were identified by the CE Work Group as central to this process: influences relating to CE Group membership, influences created by the proximal social environment, influences stemming from social interactions. Eleven measures assess these influences, and by time of publication, will have been administered to well over 7,000 9-10 year-old children and one of their parents. Our report presents baseline data on psychometric characteristics (mean, standard deviation, range, skewness, coefficient alpha) of all measures within the battery. Effectiveness of the battery in differentiating 9-10 year olds who were classified as at higher and lower risk for marijuana use in adolescence was also evaluated. Psychometric characteristics on all measures were good to excellent; higher vs. lower risk contrasts were significant in areas where risk differentiation would be anticipated.

Retention efforts are critical to maintain relationships with research participants over time. This is especially important for the Adolescent Brain Cognitive Development (ABCD) study, where families are asked to stay engaged with the study throughout the course of 10 years. This high-degree of involvement is essential to longitudinally track child and adolescent development. At a minimum, we will connect with families every 6 months by telephone, and every year in person, with closer contact with the youth directly as they transition into adolescence. Differential retention, when related to non-random issues pertaining to demographic or risk features, can negatively impact the generalizability of study outcomes. Thus, to ensure high rates of retention for all participants, the ABCD study employs a number of efforts to support youth and families. This overview details the framework and concrete steps for retention.

The Adolescent Brain Cognitive Development Study (ABCD) will capture a breadth of multi-faceted biobehavioral, environmental, familial, and genetic longitudinal developmental open-access data from over 11,000 9-10 year olds throughout the United States of America (USA) for an envisioned ten-year span. This will subsequently represent the largest study ever attempted with this level of brain phenotypic detail. This study holds the opportunity for exciting advances in the understanding of typical adolescent neurodevelopment, discovery of neurodevelopmental underpinnings of mental illness, as well as the neurodevelopmental influences of (and on) social factors, substance use, and critically - their interaction. This project will certainly take unprecedented steps in informing the nature of adolescence and the developing brain. The scale and open-access features of ABCD also necessarily entail areas for consideration to enhance the integrity of the ABCD study, and protect against potential misuse and misinterpretation of ABCD data. Ultimately, with the open-source data, all scientists in the broader community have as much responsibility as the investigators within the Consortium to treat these data with care. It will be fascinating to see what dynamic data these paths generate. ABCD is poised to exemplify how large-scale longitudinal developmental neuroscientific studies can be designed and efficiently conducted.

The Adolescent Brain Cognitive Development^SM (ABCD) study is a longitudinal study of adolescent brain development and health that includes over 11,800 youth in the United States. The ABCD study includes broad developmental domains, and gender and sexuality are two of these with noted changes across late childhood and early adolescence. The Gender Identity and Sexual Health (GISH) workgroup recommends measures of gender and sexuality for the ABCD study, prioritizing those that are developmentally sensitive, capture individual differences in the experience of gender and sexuality, and minimize participant burden. This manuscript describes the gender and sexuality measures used in ABCD and provides guidance for researchers using these data. Data showing the utility of these measures and longitudinal trends are presented. Including assessment of gender and sexuality in ABCD allows for characterization of developmental trajectories of gender and sexuality, and the broad scope of ABCD data collection allows examination of identity development in an intersectional manner.