Comparison of reading and spelling in patients with probable Alzheimer's disease

Patients with probable Alzheimer's disease (AD) are reported to show mild, but reliable, difficulties reading aloud and spelling to dictation exceptio n words, which have unusual or unpredictable correspondence between their s pelling and pronunciation (e.g. touch). To understand the cognitive dysfunc tion responsible for these impairments, 21 patients and 27 age-and educatio n-matched controls completed specially designed tests of single-word oral r eading and spelling to dictation. AD patients performed slightly below cont rols on all tasks and showed mildly exaggerated regularity effects (i.e., t he difference in response accuracy between words with regular spellings min us exception words) in reading and spelling. Qualitative analyses, however, did not demonstrate response patterns consistent with impairment in centra l lexical orthographic processing. The authors conclude that the mild alexi a and agraphia in AD reflect semantic deficits and nonlinguistic Impairment s rather than a specific disturbance in lexical orthographic processing.