MRI Neuroanatomy in Young Girls With Autism
To test the hypothesis that young girls and boys with autism exhibit different profiles of neuroanatomical abnormality relative to each other and relative to typically developing children.
Structural magnetic resonance imaging was used to measure gray and white matter volumes (whole cerebrum, cerebral lobes, and cerebellum) and total brain volume in nine girls (ages 2.29-5.16) and 27 boys (ages 1.96-5.33) with autism and 14 girls (ages 2.17-5.71) and 13 boys (ages 1.72-5.50) with typical development. Structure size and the relationship between size and age were examined. Diagnostic and cognitive outcome data were obtained after the children reached 4 to 5 years of age.
Girls with autism exhibited nearly every size-related abnormality exhibited by boys with autism. Furthermore, additional sites of abnormality were observed in girls, including enlargement in temporal white and gray matter volumes and reduction in cerebellar gray matter volume. Significant correlations were observed between age and white matter volumes (e.g., cerebral white matter rs = 0.950) for the girls with autism, whereas no significant age-structure size relationships were observed for the boys with autism.
Results suggest sex differences in etiological factors and the biological time course of the disorder.
Available from: Susan L Rossell
- "The literature investigating neurobiological sex differences in ASD is extremely limited. There is some evidence indicating that affected females may have more severe or more widespread structural abnormalities than affected males (Beacher et al. 2012; Bloss and Courchesne 2007; Lai et al. 2013; Schumann et al. 2009, 2010), though a recent investigation found no sex differences in white matter microstructure (reflective of structural connectivity) among high functioning adults with ASD (Kirkovski et al. 2015). To date, only one study has investigated neurobiological sex differences in ASD using functional magnetic resonance imaging (fMRI). "
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ABSTRACT: The medial prefrontal cortex (mPFC) and the right temporo-parietal junction (rTPj) are highly involved in social understanding, a core area of impairment in autism spectrum disorder (ASD). We used fMRI to investigate sex differences in the neural correlates of social understanding in 27 high-functioning adults with ASD and 23 matched controls. There were no differences in neural activity in the mPFC or rTPj between groups during social processing. Whole brain analysis revealed decreased activity in the posterior superior temporal sulcus in males with ASD compared to control males while processing social information. This pattern was not observed in the female sub-sample. The current study indicates that sex mediates the neurobiology of ASD, particularly with respect to processing social information.
Journal of Autism and Developmental Disorders 11/2015; DOI:10.1007/s10803-015-2639-7 · 3.06 Impact Factor
Available from: PubMed Central
- "Most studies thus far that have reported on gender effects have not found significant differences in which brain areas are affected, although the magnitude of effects in areas has tended to be larger in females (Bloss and Courchesne, 2007; Schumann et al., 2009, 2010; Calderoni et al., 2012). One study however found reduced cerebral GM and WM volumes and reduced temporal GM volumes in females versus males with ASD; in addition, cerebral, frontal, parietal, and occipital WM volumes were only correlated with age in girls but not in boys (Bloss and Courchesne, 2007). This was consistent with the gender effects observed in a meta-analysis of brain structural differences in ASD, which found that differences in the cerebellum were more likely to be observed when there were fewer males included in the study, suggesting that females may be contributing greater differences (Stanfield et al., 2008). "
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ABSTRACT: Autism spectrum disorders (ASD) display significant heterogeneity. Although most neuroimaging studies in ASD have been designed to identify commonalities among affected individuals, rather than differences, some studies have explored variation within ASD. There have been two general types of approaches used for this in the neuroimaging literature to date: comparison of subgroups within ASD, and analyses using dimensional measures to link clinical variation to brain differences. This review focuses on structural and functional magnetic resonance imaging studies that have used these approaches to begin to explore heterogeneity between individuals with ASD. Although this type of data is yet sparse, recognition is growing of the limitations of behaviorally defined categorical diagnoses for understanding neurobiology. Study designs that are more informative regarding the sources of heterogeneity in ASD have the potential to improve our understanding of the neurobiological processes underlying ASD.
Frontiers in Human Neuroscience 10/2013; 7:733. DOI:10.3389/fnhum.2013.00733 · 3.63 Impact Factor
Available from: Philip michael john Wilson
- "Previous studies have observed reduction in cerebellar grey matter volume in girls with ASD aged between two and six years  and increased cerebellar white matter volume (increased by 39%), no enlargement of cerebellar gray matter, and reduced vermis lobules VI-VII in two- and three-year-old ASD children . Sparks et al.  found an increase of 7% in the volume of the whole cerebellum in three- and four-year-old ASD children. "
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ABSTRACT: Despite the widely-held understanding that the biological changes that lead to autism usually occur during prenatal life, there has been relatively little research into the functional development of the brain during early infancy in individuals later diagnosed with autism spectrum disorder (ASD).
This review explores the studies over the last three years which have investigated differences in various brain regions in individuals with ASD or who later go on to receive a diagnosis of ASD.
We used PRISMA guidelines and selected published articles reporting any neurological abnormalities in very early childhood in individuals with or later diagnosed with ASD.
Various brain regions are discussed including; the amygdala; cerebellum; frontal cortex and lateralised abnormalities of the temporal cortex during language processing. This review discusses studies investigating head circumference, electrophysiological markers and inter-hemispheric synchronisation. All the recent findings from the beginning of 2009 across these different aspects of defining neurological abnormalities are discussed in light of earlier findings.
The studies across these different areas reveal the existence of atypicalities in the first year of life, well before ASD is reliably diagnosed. Cross-disciplinary approaches are essential to elucidate the pathophysiological sequence of events that lead to ASD.
Behavioural neurology 08/2013; 2014(3). DOI:10.3233/BEN-130350 · 1.45 Impact Factor
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