title: Cognitive subtypes of dyslexia.
abstract: Different theories conceptualise dyslexia as either a phonological, attentional, auditory, magnocellular, or automatisation deficit. Such heterogeneity suggests the existence of yet unrecognised subtypes of dyslexics suffering from distinguishable deficits. The purpose of the study was to identify cognitive subtypes of dyslexia. Out of 642 children screened for reading ability 49 dyslexics and 48 controls were tested for phonological awareness, auditory discrimination, motion detection, visual attention, and rhythm imitation. A combined cluster and discriminant analysis approach revealed three clusters of dyslexics with different cognitive deficits. Compared to reading-unimpaired children cluster no. 1 had worse phonological awareness; cluster no. 2 had higher attentional costs; cluster no. 3 performed worse in the phonological, auditory, and magnocellular tasks. These results indicate that dyslexia may result from distinct cognitive impairments. As a consequence, prevention and remediation programmes should be specifically targeted for the individual child's deficit pattern.
authors.affiliation: Research Centre Julich, Institute of Neurosciences and Biophysics, Jülich, Germany. s.heim@fz-juelich.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Heim
authors.forename: Julia
authors.initials: J
authors.lastname: Tschierse
authors.forename: Katrin
authors.initials: K
authors.lastname: Amunts
authors.forename: Marcus
authors.initials: M
authors.lastname: Wilms
authors.forename: Simone
authors.initials: S
authors.lastname: Vossel
authors.forename: Klaus
authors.initials: K
authors.lastname: Willmes
authors.forename: Anna
authors.initials: A
authors.lastname: Grabowska
authors.forename: Walter
authors.initials: W
authors.lastname: Huber
mesh_terms: D000161:Acoustic Stimulation; D000704:Analysis of Variance; D001364:Awareness / Q000502:physiology; D002648:Child; D003071:Cognition / Q000145:classification* / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology; D004410:Dyslexia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009483:Neuropsychological Tests; D011594:Psychometrics; D011932:Reading; D012044:Regression Analysis; D011795:Surveys and Questionnaires