COMPARISON BETWEEN ORAL AND WRITTEN SPELLING IN ALZHEIMERS-DISEASE

Written and oral spelling were compared in 33 patients with Alzheimer' s disease (AD) and 25 control subjects. AD patients had poorer spellin g results which were influenced by orthographic difficulty and word fr equency, but not by grammatical word class. Lexical spelling was also more deteriorated than phonological spelling. Moreover, oral spelling was more impaired than written spelling in AD patients, whereas no dif ference was present between oral and written spelling of controls. Ana lysis of spelling errors showed that, for controls, errors were predom inantly phonologically accurate in both spelling tasks. Significantly, AD patients produced more phonologically accurate than inaccurate err ors in written spelling, whereas these errors did not differ in oral s pelling. In contrast to controls who produced more constant than varia ble responses in oral and written spelling, AD patients made more vari able responses (words correctly spelled in one task but incorrectly in the other) and they showed many instances of variable errors (differe nt misspellings from one spelling task to the other). Two stepwise reg ression procedures showed that written misspellings were specifically correlated with language impairment, whereas oral spelling errors were correlated with attentional and language disorders. These results sug gest that AD increases the attentional demands of oral spelling proces s as compared to written spelling. This dissociation argues, either fo r a unique Graphemic Buffer in which oral spelling requires more atten tional resources than written spelling or for the hypothesis of separa te buffers for oral and written spelling. (C) 1996 Academic Press, Inc .