A Prospective Study of Environmental Exposures and Early Biomarkers in Autism Spectrum Disorder: Design, Protocols, and Preliminary Data from the MARBLES Study.

BACKGROUND: Until recently, environmental factors in autism spectrum disorder (ASD) were largely ignored. Over the last decade, altered risks from lifestyle, medical, chemical, and other factors have emerged through various study designs: whole population cohorts linked to diagnostic and/or exposure-related databases, large case-control studies, and smaller cohorts of children at elevated risk for ASD. OBJECTIVES: This study aimed to introduce the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) prospective study and its goals, motivate the enhanced-risk cohort design, describe protocols and main exposures of interest, and present initial descriptive results for the study population. METHODS: Families having one or more previous child with ASD were contacted before or during a pregnancy, and once the woman became pregnant, were invited to enroll. Data and biological samples were collected throughout pregnancy, at birth, and until the child's third birthday. Neurodevelopment was assessed longitudinally. The study began enrolling in 2006 and is ongoing. RESULTS: As of 30 June 2018, 463 pregnant mothers have enrolled. Most mothers ([Formula: see text]) were thirty years of age or over, including 7.9% who are fourty years of age or over. The sample includes 22% Hispanic and another 25% nonHispanic Black, Asian, or multiracial participants; 24% were born outside the United States. Retention is high: 84% of participants whose pregnancies did not end in miscarriage completed the study or are still currently active. Among children evaluated at 36 months of age, 24% met criteria for ASD, and another 25% were assessed as nonASD nontypical development. CONCLUSION: Few environmental studies of ASD prospectively obtain early-life exposure measurements. The MARBLES study fills this gap with extensive data and specimen collection beginning in pregnancy and has achieved excellent retention in an ethnically diverse study population. The 24% familial recurrence risk is consistent with recent reported risks observed in large samples of siblings of children diagnosed with ASD. https://doi.org/10.1289/EHP535.

Infant siblings and the investigation of autism risk factors.

Infant sibling studies have been at the vanguard of autism spectrum disorders (ASD) research over the past decade, providing important new knowledge about the earliest emerging signs of ASD and expanding our understanding of the developmental course of this complex disorder. Studies focused on siblings of children with ASD also have unrealized potential for contributing to ASD etiologic research. Moving targeted time of enrollment back from infancy toward conception creates tremendous opportunities for optimally studying risk factors and risk biomarkers during the pre-, peri- and neonatal periods. By doing so, a traditional sibling study, which already incorporates close developmental follow-up of at-risk infants through the third year of life, is essentially reconfigured as an enriched-risk pregnancy cohort study. This review considers the enriched-risk pregnancy cohort approach of studying infant siblings in the context of current thinking on ASD etiologic mechanisms. It then discusses the key features of this approach and provides a description of the design and implementation strategy of one major ASD enriched-risk pregnancy cohort study: the Early Autism Risk Longitudinal Investigation (EARLI).

A second reporter matters: agreement between parents' and children's reports of smoking bans in families.

BACKGROUND: Home and car smoking bans implemented by caregivers are important approaches to reducing children's secondhand smoke (SHS) exposure and attendant health risks. Such private smoking bans are usually informal and are subject to individuals' interpretation, observation, and recall. Relying on a single reporter may lead to misclassification of bans in families. PURPOSE: To determine (1) proportion of families with discordant reports of bans; (2) association between parent-child report agreement and SHS exposure; and (3) whether including a second reporter of bans improves prediction of child SHS exposure. METHODS: In each of 386 participating families a preteen and a parent reported separately on their home and car smoking bans, and agreement was determined. ANOVA, chi-square, and multiple linear regression were used to determine relationships between SHS exposure (measured by urine cotinine and reported exposure) and home/car smoking bans reported by preteens and parents. RESULTS: In 19% of families, reports disagreed for home smoking bans; 30%, for car smoking bans. Families who agreed on the presence of a ban had the lowest exposure, families who agreed on the absence of a ban had the highest exposure, and intermediate exposure for those who disagreed. Parent and child reports of bans each explained significant, unique variance in child SHS exposure. CONCLUSIONS: Due to relatively high prevalence of discordant reporting, a more accurate classification of home/car smoking bans may result from including multiple reporters.