Abstract
Recent studies suggest that both cortical gray and white-matter microstructural characteristics are distinct for subjects with autism. There is a lack of evidence regarding how these characteristics change in a developmental context. We analysed a longitudinal/cross-sectional dataset of 402 magnetic resonance imaging (MRI) scans (171 subjects with autism and 231 with typical development) from the Autism Brain Imaging Data Exchange, cohorts I–II (ABIDE-I-II). In the longitudinal sample, we computed the rate of change in the white–gray contrast, a measure which has been related to age and cognitive performance, at the boundary of the cerebral cortex. Then, we devised an analogous metric for the cross-sectional sample of the ABIDE dataset to measure age-related differences in cortical contrast. Further, we developed a probabilistic model to predict the diagnostic group in the longitudinal sample of the cortical contrast change data, using results obtained from the cross-sectional sample. In both subsets, we observed a similar overall pattern of greater decrease within the autistic population in intensity contrast for most cortical regions (81%), with occasional increases, mostly in primary sensory regions. This pattern correlated well with raw and calibrated behavioural scores. The prediction results show 76% accuracy for the whole-cortex diagnostic prediction and 86% accuracy in prediction using the motor system alone. Our results support a contrast change analysis strategy that appears sensitive in predicting diagnostic outcome and symptom severity in autism spectrum disorder, and is readily extensible to other MRI-based studies of neurodevelopmental cohorts.
Highlights
Autism spectrum disorder (ASD) is a complex and heterogeneous cluster of developmental abnormalities characterised by disrupted social reciprocity, repetitive behaviours and restricted interests[1]
Cross-sectional partial least squares (PLS) results The four groups assembled for the PLS analyses for the cross-sectional data (ASDSIEMENS, TDSIEMENS, ASDPHILIPS and TDPHILIPS) showed a similar pattern of overall greater decrease of the cortical tissue contrast for the ASD subjects as compared to typical development (TD) controls (design scores: (0.11, −0.2, 0.74, −0.64); see Fig. 1d)
The most prominent white–gray contrast (WGC) increase in ASD as compared to TD was observed in early visual areas, most of the remaining cortex featured predominant decrease in ASD as compared to TD (Fig. 1e, f)
Summary
Autism spectrum disorder (ASD) is a complex and heterogeneous cluster of developmental abnormalities characterised by disrupted social reciprocity, repetitive behaviours and restricted interests[1]. Such behavioural abnormalities are found to have certain brain-structural and physiological correlates on the level of the cortical gray matter (GM)[2,3,4]. We take this approach one step further, taking into account the fact that ASD is a developmental disorder and crucial information can be retrieved from age-related neuroanatomical changes[14,15]. Instead of measuring absolute ASD-TD group differences in WGC, we assess how this contrast changes with age, in longitudinal and cross-sectional contexts
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