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White matter correlates of attention and hyperactivity in children with Developmental Dyslexia and Attention‑deficit/Hyperactivity disorder
Poster Session E, Sunday, September 14, 11:00 am - 12:30 pm, Field House
Nilgoun Bahar1, Ellie Carpenter1, Margo Kersey1, Nick Wellman1, Rian Bogley1, Dolce Martin-Moreno1, Sarah M. Inkelis1, Pedro Pinheiro-Chagas1, Aaron Sheffler2, Zachary Miller1, Christa Pereira1, Andreas Rauschecker3, Maria Luisa Gorno-Tempini1, Maria Luisa Mandelli1; 1Department of Neurology, Dyslexia Center, UCSF, San Francisco, CA, USA, 2Department of Biostatistics, University of California, San Francisco, San Francisco, CA, USA, 3Department of Radiology & Biomedical Imaging, UCSF, San Francisco, CA, USA
Introduction: Developmental Dyslexia (DD) and Attention‑Deficit/Hyperactivity Disorder (ADHD) co‑occur in about one-third of affected children, yet the neural basis of this co-occurrence remains poorly understood. Both conditions present with differences in white‑matter (WM) organization, but it is unclear whether they affect similar or distinct pathways. We investigated the relationship between diffusion‑derived metrics and measures of inattention, hyperactivity, and reading comprehension in a large cohort with a range of reading and attentional abilities. We tested (i) which WM tracts are associated with inattention, hyperactivity, and reading comprehension, and (ii) whether these tracts show microstructural differences across diagnostic groups. Methods: 166 participants (7–16 years) met the criteria for DD-only (n=80), DD + ADHD (n=52), ADHD‑only (n=12), and typically developing (TD, n=22). Participants completed a neuropsychological battery including reading, language, attention, and executive function assessments, and underwent a 3T diffusion-weighted MRI scan. The following WM tracts were reconstructed using the pyAFQ: direct and posterior arcuate fasciculi (AF, pAF), superior longitudinal fasciculi (SLF), frontal-striatal and -aslant tracts, anterior and superior frontal callosal segments. Linear regression models were used to predict parent-reported BASC-3 Attention and Hyperactivity scores and GORT-5 Reading Comprehension scores using mean fractional anisotropy (FA) as imaging metric. All models controlled for age, sex, and intracranial volume. Planned contrasts were conducted to assess group differences. Results: Group comparisons showed that the ADHD-only and DD + ADHD groups had significantly higher inattention (F=29.09, p<.001) and hyperactivity (F=23, p<.001) than both TD and DD-only groups. Compared with TD, the ADHD-only, DD-only, and DD + ADHD groups all had significantly poorer reading comprehension (F=12.54, p<.001), with no differences between the dyslexic groups. Across the cohort, greater inattention was linked to lower FA in the left (t=-2.05, p=.04) and right SLF (t=-2.89, p=.004). Hyperactivity was associated with lower FA in the anterior frontal callosal tract (t=-2.15, p=.03) and right frontal‑aslant tract (t=-2.42, p=.01). Better reading comprehension was associated with higher FA in the left (t=1.96, p=.05) and right pAF (t=3.07, p=.002), left SLF (t=2.04, p=.04), and superior frontal callosal section (t=2.09, p=.03). Significant group differences in FA emerged in the right (F=3.17, p=.02) and left SLF (F=4.25, p=.006), with lower FA in participants with DD + ADHD and ADHD-only compared with TD. Discussion: Our analyses reveal partially dissociable WM substrates for inattention and hyperactivity, and reading comprehension in DD. Lower FA in the right SLF (and to a lesser extent, the left) was linked to inattention. This reduction was most pronounced in the co-occurring DD + ADHD and ADHD-only groups, supporting the idea of a dorsal-attention bottleneck, possibly due to delayed myelination or pruning. Hyperactivity mapped onto microstructural variation in the anterior‑frontal callosal segment and right frontal‑aslant tract, which may suggest involvement of inter‑hemispheric and premotor control loops. Reading comprehension was associated with higher FA in key nodes of the dorsal language network, highlighting the functional separability of language and attention circuitry. These findings lay groundwork for delineating circuit‑specific associations of DD and ADHD, and may inform the development of neurobiologically-grounded interventions to support the affected children.
Topic Areas: Disorders: Developmental, Reading