Abstract

Data on deficits underlying developmental dyslexia are very contradictory probably due to the variable manifestation of the disorder and the heterogeneity of dyslexic subjects in different samples. The aim of this study is two fold: a) to verify whether phonological deficits are a common marker of all cases of dyslexia b) to evaluate whether there is a link between the reading deficit and the neuropsychological profile. An extensive neuropsychological assessment was performed on 65 children with developmental dyslexia. Those who had presented a delay of language acquisition in the preschool years (RL) performed significantly worse than the dyslexics without previous language delay (NoRL) in several measures of verbal efficiency and in working memory tests. Moreover, the children in group RL, matched to those of group NoRL in terms of reading speed, made more errors in reading and writing tasks. These findings suggest that the "verbal deficit hypothesis" of dyslexia should not be generalized to all cases of developmental dyslexia, but to a subset of children with language delay. Deficits underlying the acquisition of the written code could be of a different nature in different populations of dyslexic children. The aim of future researches should be to identify the critical deficits underlying different types of reading disorders.