Vanderauwera, J. 1, 2 , Vandermosten, M. 1, 2 , Wouters, J. 2 & Ghesquière, P. 1
1 Parenting and Special Education Research Unit, Faculty of Psychology and Educational Sciences, KU Leuven, Belgium
2 Research Group ExpORL, Department of Neurosciences, KU Leuven, Belgium
Developmental dyslexia is characterized by severe and persistent reading and/or spelling problems. Despite being the most common learning disability, we do not yet understand its core neurobiological cause(s). In adults and school-aged children with dyslexia neurobiological anomalies have been demonstrated, however in these studies causal from consequential effects are intertwined. Therefore, we collected diffusion MRI and reading-related behavioural data in a large group of 61 pre-readers, of whom 15 developed dyslexia later on. We followed them up until they had two years of reading experience, thereby capturing the dynamics of these neurobiological deficits. We investigated white matter pathways relevant for reading aspects, i.e. the dorsal arcuate fasciculus (AF) and the ventral inferior fronto-occipital fasciculus (IFOF), both at the pre-reading and the beginning reading stage. We provide the first evidence that children diagnosed with dyslexia already exhibit white matter anomalies prior to reading instruction in the left dorsal pathway, with unique predictive power above and beyond cognitive and familial risk measures. Our findings hold the potential to increase the sensitivity and specificity of an early diagnosis and can lead to more effective early interventions.