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

https://doi.org/10.1016/j.jaac.2014.07.007Get rights and content

Objective

Although 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 nonlinear 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.

Section snippets

Participants

The Baby Siblings Research Consortium (BSRC) is an international network dedicated to studying early development in infants at increased risk of ASD. The present analyses included data from 12 BSRC sites (University of Alberta, Dalhousie University, Kennedy Krieger Institute, McMaster University, University of California, Davis, University of California, Los Angeles, University of California, San Diego, University of Miami, University of Pittsburgh, University of Toronto, Vanderbilt University,

Results

The final dataset consisted of 695 participants, including 442 HR infants (77 HR-ASD, 32 HR-DD, and 333 HR-TD) and 253 LR infants. LR children with ASD (n = 7) or DD (n = 15) were excluded, as the numbers were too small for formal group comparisons. Sex ratio varied by group (χ2 = 31.4, df = 3, p < .001); pairwise comparisons indicated that a higher proportion of boys were found in the HR-ASD (72.7%) and HR-DD (84.4%) groups compared to HR-TD (45.9%) and LR (53.8%) groups. There were no group

Discussion

This study examined early head growth in ASD using a prospective design (complemented by retrospective growth records to increase the density of measurement in the first year), and is the first to compare high-risk children with ASD to nondiagnosed high-risk children and community controls using longitudinal growth models. There are several intriguing findings. First, there are no significant differences in the overall model comparing head growth between HR infants (regardless of outcome) and

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    This article is discussed in an editorial by Dr. Armin Raznahan on page 1045.

    Autism Speaks provided funding to establish the Baby Siblings Research Consortium (BSRC) database, used for the study analyses. Data collection at contributing sites was supported by grants from the National Institutes of Health (NIH: HD54979, J.I.; MH059630, R.L.; HD052804, K.D., L.C.; HD043292, W.S.; HD047417, D.M.; HD0057284, D.M, W.S; MH068398, S.O.; HD055784 and MH096961, T.H.), the Canadian Institutes of Health Research (62924 and 102665, S.E.B., J.B., L.Z.), Autism Speaks (J.I., W.S.), Autism Speaks Canada (S.E.B., J.B., L.Z.), and NeuroDevNet (S.E.B., J.B., L.Z.).

    Dr. Gregory S. Young served as the statistical expert for this research.

    The authors thank Alycia Halliday, PhD, of Autism Speaks, for organizational support, and members of the BSRC for their input and guidance. The authors also thank the children and families who participated in this research.

    Disclosures: Dr. Zwaigenbaum is the site PI of a study sponsored by SynapDx (receives operating funds but no honoraria). Drs. Young, Stone, Dobkins, Ozonoff, Brian, Bryson, Carver, Hutman, Iverson, Landa, and Messinger report no biomedical financial interests or potential conflicts of interest.

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    Copyright © 2014 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.