Biospecimens and the ABCD study: Rationale, methods of collection, measurement and early data

Abstract

Biospecimen collection in the Adolescent Brain Cognitive Development (ABCD) study - of hair samples, shed deciduous (baby) teeth, and body fluids - will serve dual functions of screening for study eligibility, and providing measures of biological processes thought to predict or correlate with key study outcomes on brain and cognitive development. Biosamples are being collected annually to screen for recency of drug use prior to the neuroimaging or cognitive testing visit, and to store for the following future studies: (1) on the effects of exposure to illicit and recreational drugs (including alcohol and nicotine); (2) of pubertal hormones on brain and cognitive developmental trajectories; (3) on the contribution of genomics and epigenomics to child and adolescent development and behavioral outcomes; and (4) with pre- and post-natal exposure to environmental neurotoxicants and drugs of abuse measured from novel tooth analyses. The present manuscript describes the rationales for inclusion and selection of the specific biospecimens, methodological considerations for each measure, future plans for assessment of biospecimens during follow-up visits, and preliminary ABCD data to illustrate methodological considerations.

Keywords: ABCD study; Biospecimens; Environmental exposures; Genetics; Gonadal hormones; Substance use.

Fig. 1

Variations in waking time across ABCD participants and sites. Salivary hormone levels are influenced by circadian patterns in hormone secretion, which is largely impacted by time of waking.

Fig. 2

Variations in duration of saliva collection times across ABCD participants and sites. The amount of time it takes a participant to complete the passive drool sampling process can influence the concentration of pubertal hormone levels.

Fig. 3

Percentage of parents/guardian of over 2000 ABCD participants studied so far who endorse use of Alcohol, Cocaine, Marijuana and Tobacco both before and after pregnancy recognition.

Fig. 4

Schematic of tooth development (Arora et al., 2012). (a) Earliest deposition of dentine (grey area) at DEJ at cusp tip (b) Continued extension of dentine (and enamel) towards the tooth cervix. (c) Neonatal line (NL), a histological feature, formed at the time of birth (d) Completion of enamel and primary dentine formation between 2–11 postnatal months depending on tooth type. Secondary dentine continues forming at pulpal margin (not shown). (e) Confocal laser scanning micrograph of NL in enamel.