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

Abstract

BackgroundLarge controversy exists regarding the potential existence and clinical significance of larger brain volumes in toddlers who later develop autism. Assessing this relationship is important for determining the clinical utility of early head circumference (HC) measures and for assessing the validity of the early overgrowth hypothesis of autism, which suggests that early accelerated brain development may be a hallmark of the disorder.MethodsWe performed a retrospective comparison of HC, height, and weight measurements between 66 toddlers who were later diagnosed with autism and 66 matched controls. These toddlers represent an unbiased regional sample from a single health service provider in the southern district of Israel. On average, participating toddlers had >8 measurements between birth and the age of two, which enabled us to characterize individual HC, height, and weight development with high precision and fit a negative exponential growth model to the data of each toddler with exceptional accuracy.ResultsThe analyses revealed that HC sizes and growth rates were not significantly larger in toddlers with autism even when stratifying the autism group based on verbal capabilities at the time of diagnosis. In addition, there were no significant correlations between ADOS scores at the time of diagnosis and HC at any time-point during the first 2 years of life.ConclusionsThese negative results add to accumulating evidence, which suggest that brain volume is not necessarily larger in toddlers who develop autism. We believe that conflicting results reported in other studies are due to small sample sizes, use of misleading population norms, changes in the clinical definition of autism over time, and/or inclusion of individuals with syndromic autism. While abnormally large brains may be evident in some individuals with autism and more clearly visible in MRI scans, converging evidence from this and other studies suggests that enlarged HC is not a common etiology of the entire autism population. Early HC measures, therefore, offer very limited clinical utility for assessment of autism risk in the general population.Electronic supplementary materialThe online version of this article (doi:10.1186/s13229-017-0129-9) contains supplementary material, which is available to authorized users.

Skeletal Growth Dysregulation in Australian Male Infants and Toddlers With Autism Spectrum Disorder

“…Some studies found increased weight in infants with ASD from as early as 1–3 months [Fukumoto et al, ; Mraz et al, ; van Daalen et al, ], other studies have reported no differences in weight until 4‐ [Torrey et al, ], 6‐ [Surén et al, ], or 11 months of age [Chawarska et al, ], or not at all [Mraz et al, ], when compared to TD infants. Similar to Dinstein et al [] the current study found that infants with ASD were lighter in weight at birth compared to TD infants; however, contrary to the earlier finding of Dissanayake et al [], infants and toddlers with ASD in our study did not display an increased acceleration in weight from birth through 3 years of age relative to the TD infants.…”

“…While studies have reported findings of “accelerated” growth in ASD, this term has been used to reflect a trend to increase in physical measures in individual age groups and is almost always used in reference to head and brain measures, rather than height and weight. In addition to Dissanayake et al [] and Dinstein et al [], the current study is the only other study to date to examine the rate of growth across all three physical parameters of HC, height, and weight from birth to three years of age; it is also the only study to examine these growth parameters in a large representative group of participants with ASD during these early years.…”

“…A recent study of 66 toddlers who were later diagnosed with ASD compared to matched controls found that while toddlers with ASD were significantly smaller in size for HC and weight at birth (height was not measured at birth), there were no significant differences in size for HC, height, or weight from three months through three years of age [Dinstein et al, ]. The authors pointed to methodological differences between their study and many previous studies which have found differences in size between toddlers with ASD compared to controls, namely the use of a local control group, and the potential confounds of including children with genetic syndromes and the changing diagnostic criteria.…”

“…Although most studies have reported increased HC and height in infants and toddlers with ASD compared to those who are TD, several studies have found no difference in growth in HC or height between the two groups [Barnard‐Brak, Sulak, & Ivey Hatz, ; Dinstein, Haar, Atsmon, & Schtaerman, ; Mraz et al, ; Riikonen et al, ; van Daalen et al, ; Vanhala, Turpeinen, & Riikonen, ; Zwaigenbaum et al, ]. A large longitudinal study of growth in infants and toddlers aged 1–3 years examined measurements of HC and height in high‐risk siblings (i.e., children with a sibling with ASD) as well as TD infants from the community, and infants with a developmental delay [Zwaigenbaum et al, ].…”

“…Additionally, Vanhala et al did not recruit TD participants, but instead reported that the HC of their ASD participants were within the normal limits. The use of control groups not representative of the general population is problematic in this field of research [Dinstein et al, ; Green et al, ]. Local control groups of TD children often differ quite dramatically from normative data.…”