title: Cognitive subtypes of dyslexia are characterized by distinct patterns of grey matter volume.
abstract: The variety of different causal theories together with inconsistencies about the anatomical brain markers emphasize the heterogeneity of developmental dyslexia. Attempts were made to test on a behavioral level the existence of subtypes of dyslexia showing distinguishable cognitive deficits. Importantly, no research was directly devoted to the investigation of structural brain correlates of these subtypes. Here, for the first time, we applied voxel-based morphometry (VBM) to study grey matter volume (GMV) differences in a relatively large sample (n = 46) of dyslexic children split into three subtypes based on the cognitive deficits: phonological, rapid naming, magnocellular/dorsal, and auditory attention shifting. VBM revealed GMV clusters specific for each studied group including areas of left inferior frontal gyrus, cerebellum, right putamen, and bilateral parietal cortex. In addition, using discriminant analysis on these clusters 79% of cross-validated cases were correctly re-classified into four groups (controls vs. three subtypes). Current results indicate that dyslexia may result from distinct cognitive impairments characterized by distinguishable anatomical markers.
authors.affiliation: Laboratory of Psychophysiology, Department of Neurophysiology, Nencki Institute of Experimental Biology, Pasteur 3, 02-093, Warsaw, Poland, k.jednorog@nencki.gov.pl.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Jednoróg
authors.forename: Natalia
authors.initials: N
authors.lastname: Gawron
authors.forename: Artur
authors.initials: A
authors.lastname: Marchewka
authors.forename: Stefan
authors.initials: S
authors.lastname: Heim
authors.forename: Anna
authors.initials: A
authors.lastname: Grabowska
mesh_terms: D001288:Attention / Q000502:physiology; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping; D002648:Child; D016000:Cluster Analysis; D003072:Cognition Disorders / Q000145:classification* / Q000209:etiology*; D005260:Female; D066128:Gray Matter / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D011932:Reading; D013064:Speech Disorders / Q000150:complications* / Q000473:pathology*; D014888:Wechsler Scales