Brain Morphology in Autism and Fragile X Syndrome Correlates With Social IQ: First Report From the Canadian-Swiss-Egyptian Neurodevelopmental Study

Meguid, Nagwa A.; Fahim, Chérine; Yoon, Uicheul; Nashaat, Neveen Hassan; Ibrahim, Ahmed S.; Mancini-Marı̈e, Adham; Brandner, Catherine; Evans, Alan C.

doi:10.1177/0883073809341670

Cited by 18 publications

(10 citation statements)

References 59 publications

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“…This is in contrast with previous studies using GI in children, adolescents or adults with ASD, which report either an increased GI (Hardan et al, 2004; Jou et al, 2010), or an absence of significant difference (Casanova et al, 2009; Kates et al, 2009; Meguid et al, 2010). Lower intellectual abilities in our patient group may explain part of the divergence with previous results, given that both studies that reported increased GI comprised participants with higher full-scale IQ scores (means: 105 ± 16 for Hardan et al (2004), 110 ± 15 for Jou et al (2010) and 113 ± 15 for Wallace et al (2013)).…”

Section: Discussioncontrasting

confidence: 88%

“…Previous studies have noted alterations to cortical shape in autism (Levitt et al, 2003; Nordahl et al, 2007; Shokouhi et al, 2012), and some have used the Gyrification Index (GI; Hardan et al, 2004; Casanova et al, 2009; Kates et al, 2009; Jou et al, 2010; Meguid et al, 2010). Given that the cortex grows primarily through radial expansion (Rakic, 1988), the GI was specifically designed to identify early defects in cortical development.…”

Section: Introductionmentioning

confidence: 99%

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Decreased frontal gyrification correlates with altered connectivity in children with autism

Schaer¹,

Ottet²,

Scariati³

et al. 2013

Front. Hum. Neurosci.

127

104

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The structural correlates of functional dysconnectivity in autism spectrum disorders (ASD) have been seldom explored, despite the fact that altered functional connectivity is one of the most frequent neuropathological observations in the disorder. We analyzed cerebral morphometry and structural connectivity using multi-modal imaging for 11 children/adolescents with ASD and 11 matched controls. We estimated regional cortical and white matter volumes, as well as vertex-wise measures of cortical thickness and local Gyrification Index (lGI). Diffusion Tensor Images (DTI) were used to measure Fractional Anisotropy (FA) and tractography estimates of short- and long-range connectivity. We observed four clusters of lGI reduction in patients with ASD, three were located in the right inferior frontal region extending to the inferior parietal lobe, and one was in the right medial parieto-occipital region. Reduced volume was found in the anterior corpus callosum, along with fewer inter-hemispheric frontal streamlines. Despite the spatial correspondence of decreased gyrification and reduced long connectivity, we did not observe any significant relationship between the two. However, a positive correlation between lGI and local connectivity was present in all four clusters in patients with ASD. Reduced gyrification in the inferior fronto-parietal and posterior medial cortical regions lends support for early-disrupted cortical growth in both the mirror neuron system and midline structures responsible for social cognition. Early impaired neurodevelopment in these regions may represent an initial substrate for altered maturation in the cerebral networks that support complex social skills. We also demonstrate that gyrification changes are related to connectivity. This supports the idea that an imbalance between short- and long-range white matter tracts not only impairs the integration of information from multiple neural systems, but also alters the shape of the brain early on in autism.

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Section: Discussioncontrasting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Decreased frontal gyrification correlates with altered connectivity in children with autism

Schaer¹,

Ottet²,

Scariati³

et al. 2013

Front. Hum. Neurosci.

127

104

View full text Add to dashboard Cite

show abstract

“…These distinct neuroanatomical patterns are present even though multivariate pattern classification analysis using diagnostic-behavioral data could not differentiate between FXS+A and iAUT. Another recent study 25 also found neuroanatomical differences between AUT and FXS+A even though the two groups were behaviorally indistinguishable. Specifically, the group with AUT was found to have thinner cortex in the left ACC and bilateral medial PFC, as compared to the group with FXS+A.…”

Section: Commentmentioning

confidence: 80%

Neuroanatomical Differences in Toddler Boys With Fragile X Syndrome and Idiopathic Autism

Hoeft¹,

Walter²,

Lightbody³

et al. 2011

Arch Gen Psychiatry

109

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Context Autism is an etiologically heterogeneous neurodevelopmental disorder for which there is no known unifying etiology or pathogenesis. Many conditions of atypical development can lead to autism, including fragile X syndrome (FXS), which is presently the most common known single gene cause of autism. Objective To examine whole-brain morphometric patterns that discriminate young boys with FXS from those with idiopathic autism (iAUT), as well as control participants. Design Cross sectional, in-vivo neuroimaging study. Setting Academic medical centers. Patients Young boys (n=165, 1.57-4.15 years) diagnosed as FXS or iAUT as well as typically developing (TD) and idiopathic developmentally delayed (DD) controls. Main Outcome measures Univariate voxel-based morphometric (VBM) analyses, VBM multivariate pattern classification (linear support vector machine) and clustering analyses (self organizing map). Results We found that frontal and temporal grey and white matter regions often implicated in social cognition, including the medial prefrontal cortex, orbitofrontal cortex, superior temporal region, temporal pole, amygdala, insula, and dorsal cingulum, were aberrant in FXS and iAUT as compared to controls. However, these differences were in opposite directions for FXS and iAUT relative to controls; in general, greater volume was seen in iAUT compared to controls, who in turn had greater volume than FXS. Multivariate analysis showed that the overall pattern of brain structure in iAUT generally resembled that of the controls more than FXS, both with and without AUT (FXS+A, FXS-A, respectively). Conclusions Our findings demonstrate that FXS and iAUT are associated with distinct neuroanatomical patterns, and further underscores the neurobiological heterogeneity of iAUT.

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“…Nonetheless, underscoring the neurobiological heterogeneity of ASD, there are differences between ASD in FXS and ASD in the general population. Hoeft et al [78] and Meguid et al [79] have reported differences in the direction of morphologic abnormalities in the two types of ASD. Individuals with FXS, with or without ASD, have a larger caudate nucleus and smaller amygdala than their counterparts with idiopathic ASD [80].…”

Section: Neurobiological Correlates Of Asd In Fxs: Anomalies Of the Cmentioning

confidence: 99%

What Can We Learn about Autism from Studying Fragile X Syndrome?

Budimirović

Kaufmann²

2011

Dev Neurosci

162

140

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Despite early controversy, it is now accepted that a substantial proportion of children with fragile X syndrome (FXS) meets diagnostic criteria for autism spectrum disorder (ASD). This change has led to an increased interest in studying the association of FXS and ASD because of the clinical consequences of their co-occurrence and the implications for a better understanding of ASD in the general population. Here, we review the current knowledge on the behavioral, neurobiological (i.e., neuroimaging), and molecular features of ASD in FXS, as well as the insight into ASD gained from mouse models of FXS. This review covers critical issues such as the selectivity of ASD in disorders associated with intellectual disability, differences between autistic features and ASD diagnosis, and the relationship between ASD and anxiety in FXS patients and animal models. While solid evidence supporting ASD in FXS as a distinctive entity is emerging, neurobiological and molecular data are still scarce. Animal model studies have not been particularly revealing about ASD in FXS either. Nevertheless, recent studies provide intriguing new leads and suggest that a better understanding of the bases of ASD will require the integration of multidisciplinary data from FXS and other genetic disorders.

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Brain Morphology in Autism and Fragile X Syndrome Correlates With Social IQ: First Report From the Canadian-Swiss-Egyptian Neurodevelopmental Study

Cited by 18 publications

References 59 publications

Decreased frontal gyrification correlates with altered connectivity in children with autism

Decreased frontal gyrification correlates with altered connectivity in children with autism

Neuroanatomical Differences in Toddler Boys With Fragile X Syndrome and Idiopathic Autism

What Can We Learn about Autism from Studying Fragile X Syndrome?

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