Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are two neurodevelopmental disorders with distinct diagnostic criteria that often co-occur. Although both ASD and ADHD are associated with structural and functional brain abnormalities when compared to typically developing (TD) populations, it is necessary to disentangle the shared and specific abnormalities between these disorders, potentially underlying similarities and differences in their clinical and neurocognitive profiles. The aim of this thesis was to explore the shared and disorder specific functional and structural brain abnormalities between ASD and ADHD. For this purpose, the neural underpinnings of a group of children with ADHD, a group of children with ASD and a group of TD children aged 8 to 12 years old were compared using different neuroimaging techniques. In Chapter 2, the experimental sample included in this thesis was described using multiple clinical and neurocognitive measures. In the first study (Chapter 3), total and regional brain volumes were compared between groups, using voxel-based morphometry. The results of this study showed larger grey matter volume (GMV) in the left precuneus and decreased GMV in the right thalamus in the ADHD group compared to either the TD or the ASD groups, and increased GMV in the right precentral gyrus in the ASD group compared to either the ADHD or the TD groups. In the second study (Chapter 4), white matter microstructure was compared between groups using diffusion tensor imaging derived indices (fractional anisotropy [FA] and mean diffusivity [MD]). Reduced FA (i.e. reduced diffusion directionality) in the genu of the corpus callosum (CC) was found in the ASD group compared to either children with ADHD or TD children, whereas lower FA in the body of the CC was a shared feature between the ADHD and ASD groups. Finally, in the last study (Chapter 5), inhibition-related brain activation was compared between groups during the execution of an inhibition stop-signal task. In children with ADHD, successful inhibition was associated with right inferior parietal activation, whereas right frontal regions were activated in children with ASD. Between-group comparisons disclosed higher middle frontal activation in the ASD group compared to the ADHD or the TD groups. Taken together, our findings provide further evidence contributing to disentangle the shared and specific brain structural and functional abnormalities between ASD and ADHD. / Doctorat en Sciences psychologiques et de l'éducation / info:eu-repo/semantics/nonPublished
| Identifer | oai:union.ndltd.org:ulb.ac.be/oai:dipot.ulb.ac.be:2013/303539 |
| Date | 01 April 2020 |
| Creators | Albajara Saenz, Ariadna |
| Contributors | Peigneux, Philippe, Massat, Isabelle, Aeby, Alec, Colin, Cécile, Collette, Fabienne, Purper-Ouakil, Diane |
| Publisher | Universite Libre de Bruxelles, Université libre de Bruxelles, Faculté des Sciences psychologiques et de l'éducation, Bruxelles |
| Source Sets | Université libre de Bruxelles |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:ulb-repo/semantics/doctoralThesis, info:ulb-repo/semantics/openurl/vlink-dissertation |
| Format | 3 full-text file(s): application/pdf | application/pdf | application/pdf |
| Rights | 3 full-text file(s): info:eu-repo/semantics/closedAccess | info:eu-repo/semantics/openAccess | info:eu-repo/semantics/restrictedAccess |
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