Search Abstracts | Symposia | Slide Sessions | Poster Sessions
Neuroanatomical Differences in Children with Dyslexia
Poster Session C, Saturday, September 13, 11:00 am - 12:30 pm, Field House
Iria Gutierrez-Schieferl1, Alison Schug2, Ashley Vanmeter3, Guinevere Eden4; 1Georgetown University, 2Department of Neuroscience
Introduction: Developmental Dyslexia, or Reading Disability (RD), is a common learning disability marked by difficulties in word decoding that negatively affects academic and vocational outcomes. Neuroanatomical studies on RD have generally found reduced gray matter volume (GMV) in left occipitotemporal, orbitofrontal/inferior frontal, bilateral temporoparietal regions, and cerebellum (Eckert et al., 2016; Linkersdörfer et al., 2012; Richlan et al., 2013). However, findings have lacked consistency, likely due to small sample sizes, and variations in the studies’ methodologies and statistics (Ramus et al., 2018). Surface-based measures offer advantages over GMV, including providing insights into the origins of the neuroanatomical aberrations. Differences in cortical thickness (CT), which likely reflects experience, have been reported in RD (Williams et al., 2018, Kujala et al., 2021), while sulcal depth (SD), which likely reflects prenatal developmental origins, has not been investigated. The present study used a large sample, representative of the United States, and tested for neuroanatomical aberrations using CT and SD measures. Methods: We selected from the Baseline data of the ABCD Study for monolinguals with Matrix Reasoning (MR, non-verbal reasoning) >85, NIH Toolbox Picture Vocabulary Test (verbal reasoning) >70, and excluded psychiatric and neurological disorders, visual or sensory impairment. Inclusion for the RD Group was based on <85 (16th percentile) on the Toolbox Oral Reading Recognition Test at both Baseline and 2-Year Follow-Up, while it was >90 for Controls. Propensity matching ensured groups were equated on socioeconomic status (SES), and MR, resulting in 293 Control and 285 RD participants (9.53 ± 0.5 years). MRI data were preprocessed using SPM12 (Ashburner & Friston, 2000) and CAT12. T-tests compared CT and SD between the two groups, controlling for age (months), sex, non-verbal reasoning, SES, ADHD, pubertal status, and Study Site (voxel-wise height threshold p < .005 uncorrected, cluster-level extent threshold p < .05 FDR). Results: Compared to the Controls, the RD Group had less CT in two relatively small clusters around left and right insula. However, the RD group had less SD across all lobes and both hemispheres. The two largest clusters were in left and right insula cortex (the latter overlapping with the CT result) and there were eight other regions. Notably, the results overall included regions extending into brain areas associated with reading, such as left fusiform, superior temporal, inferior and middle frontal gyri; however, they also included their homotopic right-hemisphere counterparts. Of the overall volume of clusters 58% resided in the left and 43% in the right hemisphere. No regions with thinner cortex or lower sulcal depth were observed in the Control group. Conclusions: In the largest study of RD conducted under a unified protocol by relying on data from the ABCD Study, we found relatively thinner cortex in RD in left and right insula regions. However, shallower sulci were found across both hemispheres and all lobes, indicative of extensive aberrations not limited to left-hemisphere areas associated with language processing. These aberrations are likely antecedent to reading acquisition and specific in nature, given that less CT or GD was not observed in the controls.
Topic Areas: Reading, Disorders: Developmental