Similarly Expanded Bilateral Temporal Lobe Volumes in Female and Male Children With Autism Spectrum Disorder

Background: Autism spectrum disorder (ASD) is more prevalent in male than female individuals. Very few studies have examined sex modulations of brain anatomical differences between individuals with ASD and typically developing (TD) individuals, especially in children. The current study aimed to identify sex-dependent and/or sex-independent neuroanatomical mechanisms underlying ASD.

Methods: Magnetic resonance imaging data were acquired from the Autism Brain Imaging Data Exchange. A 2 (diagnosis) × 2 (sex) design was used. Subjects whose ages were between 6 and 20 years were included for analysis, with matched full-scale IQ between groups for each dataset. The resulting effective numbers of subjects were 36 female subjects with ASD, 54 TD female subjects, 182 male subjects with ASD, and 172 TD male subjects. Twenty independent gray matter (GM) and 20 white matter (WM) volume sources were estimated using source-based morphometry.

Results: Among all the independent GM and WM sources, none of them showed a significant diagnosis by sex interaction. One GM source of the bilateral inferior and middle temporal lobe showed a significantly larger volume in ASD than TD individuals and in male than in female subjects. This diagnosis effect was age sensitive and was present only in participants between 8 and 14 years of age.

Conclusions: Only sex-independent, large-scale neuroanatomical alterations could be observed in children with ASD. The directionality of bilateral temporal GM alterations was in line with the prediction of the extreme male brain hypothesis, supporting the view that similar neurobiological mechanisms may drive sexual dimorphism and the onset of ASD.