Early Head Growth in Infants at Risk of Autism: A Baby Siblings Research Consortium Study

Abstract

Objective: While early brain overgrowth is frequently reported in autism spectrum disorder (ASD), the relationship between ASD and head circumference (HC) is less clear, with inconsistent findings from longitudinal studies that include community controls. Our aim was to examine whether head growth in the first 3 years differed between children with ASD from a high-risk (HR) sample of infant siblings of children with ASD (by definition, multiplex), HR siblings not diagnosed with ASD, and low-risk (LR) controls. Method: Participants included 442 HR and 253 LR infants from 12 sites of the international Baby Siblings Research Consortium. Longitudinal HC data were obtained prospectively, supplemented by growth records. Random effects non-linear growth models were used to compare HC in HR infants and LR infants. Additional comparisons were conducted with the HR group stratified by diagnostic status at age 3: ASD (n=77), developmental delay (DD; n=32), and typical development (TD; n=333). Nonlinear growth models were also developed for height to assess general overgrowth associated with ASD. Results: There was no overall difference in head circumference growth over the first 3 years between HR and LR infants, although secondary analyses suggested possible increased total growth in HR infants, reflected by the model asymptote. Analyses stratifying the HR group by 3-year outcomes did not detect differences in head growth or height between HR infants who developed ASD and those who did not, nor between infants with ASD and LR controls. Conclusion: Head growth was uninformative as an ASD risk marker within this HR cohort.

No evidence of early head circumference enlargements in children later diagnosed with autism in Israel

“…Furthermore, the validity of early findings that were mostly based on comparisons with CDC population norms have been questioned, because these norms have underestimated the true HC distribution in the general population [18]. With this in mind, several comparisons of early HC measurements between toddlers with autism and community-matched controls did not find any significant between-group differences [19–23]. These studies demonstrate the ongoing controversy regarding the existence and clinical significance of early brain overgrowth in toddlers with autism.…”

Plausible etiology of brain dysconnectivity in autism – Review and prospectus

“…This may explain why some affected youngsters have enlarged heads [36]. IGF promotes overall growth in children; those affected with autism are typically not shorter than average following the pubertal growth spurt.…”

A review of physical growth in children and adolescents with Autism Spectrum Disorder

“…The use of control groups not representative of the general population is also problematic (Constantino et al, 2010a;Mraz et al, 2009;Raznahan et al, 2013;Zwaigenbaum et al, 2014). When compared with CDC norms, local control groups of TD children differ quite dramatically in HC, weight, and stature, suggesting that either the TD samples were not representative of the population, or that the CDC norms currently being used are outdated.…”

“…A recent longitudinal study of growth compared retrospective and prospective measurements of head circumference and height in community-based TD infants, infants with a developmental delay, and infants with an older sibling with ASD, known as "high-risk" siblings (Zwaigenbaum et al, 2014). There were no differences in growth between high-risk siblings who did and did not later receive a diagnosis of ASD (i.e., multiplex compared with simplex).…”