Developmental dyslexia

Abstract

  ʻDevelopmental Dyslexiaʼ is translated in Japanese as developmental reading and spelling disorder, be cause children with developmental dyslexia are showing both reading and spelling difficulties. Developmen tal dyslexia is not interpreted by environmental factors but cognitive factors and show discrepancy reading/spelling attainment level from expected that from age and/or intellectual level. Namely, it is needed to con duct three kinds of tests for diagnosis; general intelligence, attainment level of reading/spelling, cognitive abilities relating with reading/spelling acquisition. The prevalence of DD is thought to be affected by the writing system whether transparent (regular orthography) or opaque (irregular orthography) . The preva lence of English as opaque writing system manifested higher than that of transparent one. It is possible that children show difficulties in one written language and not in other language. As ectopia and microgyri are observed in the adults with DD, migration disorder is one of the crucial hypothesis as the biological bases for DD. Biological bases underlying DD may produce cognitive disorders, such as phonological awareness, visual cognition, and automatization disorders. Two kinds of training method based on the scientific evi dence reported using case series study design method in Japanese children with DD.