[PS-1.41] New insights on developmental dyslexia subtypes: Heterogeneity of mixed reading profiles

Zoubrinetzky, R. 1, 2 & Valdois, S. 1

1 Laboratoire de Psychologie et NeuroCognition, UMR 5105 CNRS, Université Pierre Mendès France, Grenoble, France
2 Centre Référent de Diagnostic des Troubles du Langage et des Apprentissages, Pôle Couple-Enfant, CHU de Grenoble

We examined whether classifications based on reading performance are relevant to identify cognitively homogeneous subgroups of dyslexic children. Each of the 71 dyslexic participants was selected to have a mixed reading profile, i.e. poor irregular word and pseudo-word reading performance (accuracy and speed). Despite their homogeneous reading profile, the participants were found to split into four distinct cognitive subgroups, characterized by a single phonological disorder, a single visual attention (VA) span disorder, a double deficit or none of these disorders. The two subgroups characterized by single and contrasted cognitive disorders were found to exhibit very similar reading performance but more contrasted spelling performance (quantitative analysis). A qualitative analysis showed that different cognitive disorders resulted in different error types in reading as in spelling. The overall findings disqualify subtyping based on reading profiles on words vs. pseudo-word as a classification method to identify cognitively homogeneous subgroups of dyslexic children. The present findings have important implications from a clinical perspective. Although reading profiles provide valuable information on the development of the reading system and adequate assessment of the two reading procedures functioning, it is clear from our results that they provide no reliable information on the cognitive disorders involved in the reading problem. Thus, the clinician must do additional investigations more directly targeted towards the identification of associated cognitive disorders, in order to identify which remediation program is more appropriate to improve the child?s reading performance. Specific assessment of phonological skills is required, all the more that our results indicate that poor pseudo-word reading is not a sufficient clue to conclude that an underlying phonological disorder is at play. Investigation of VA span abilities is further required as more and more evidence suggests a specific contribution of this component to normal and atypical reading and spelling.