Acquired Disorders of Reading and Writing: Cross-Script Comparisons

Abstract

Aphasiologists have accumulated a sophisticated understanding of the language impairments among English speakers. Research in the field of cognitive neuropsychology has improved our knowledge about how language becomes impaired in English speakers following brain damage by generating conceptual frameworks for understanding why language impairments occur. A large proportion of the research evidence that supports these models comes from studies of patients who have acquired problems in spoken and written naming (anomia), reading (dyslexia) and writing (dysgraphia). The ultimate aim of this research is to enhance the lives of patients with aphasia by improving diagnosis of language impairments and by development of innovative rehabilitation strategies. One outstanding issue in the field is how to exploit our advances in knowledge to other languages. Crosslinguistic studies are rare but from what we do know there can be remarkably similar patterns of language impairment following damage to specific brain regions i.e., Broca’s and Wernicke’s areas that are known to be necessary for language comprehension and production [39,42,43]. However, the early work of pioneers such as Martin Albert, Liz Bates and Loraine Obler has taught us that communication disorders must be investigated in the context of the unique linguistic properties that characterize a particular language [1]. The challenge to researchers in the field of behavioural neurology is to document how these unique linguistic properties impact on specific communication abilities. Such reports may contribute to a cognitive neuropsychological framework used to interpret patterns of aphasia within languages. In addition to improving the lives of patients, this endeavor has the potential to lead to discoveries about how the brain adapts to different language environments. For example, we now know that distinct brain areas are implicated in dyslexia in different orthographies such as Chinese and English [54]. Much of the progress in our understanding of communication disorders in English comes from cognitive neuropsychological studies of patients with selective disorders of reading, spelling and writing. For example, acquired surface dyslexia in English refers to a selective impairment to the reading aloud of irregularly spelled words particularly if the words are low in frequency and have an abstract meaning e.g., indict. This impairment is accompanied by a preserved ability to read regularly spelled words and nonwords e.g. zint. Surface dyslexic reading is characterised by regularisation errors when reading word components e.g. yacht is pronounced ‘ya/tch/ed’. Acquired surface dysgraphic patients misspell irregularly spelled words e.g. yacht→ YOT and make homophone confusions in writing e.g. write the word stake when asked to write the sentence “He had steak for dinner”. The opposite pattern of reading impairment is acquired phonological dyslexia, which refers to impaired reading of nonwords together with a preserved ability to read irregular and regular