Central and peripheral aspects of writing disorders in Alzheimer's disease.

It is currently assumed that lexical and phonological dysgraphia emerge in different stages of Alzheimer's disease (AD) as a consequence of the progressive impairment of lexical and phonological knowledge. We studied patients affected by mild and severe dementia. No differences emerged in the distribution of surface and orthographic errors in the two groups of patients. Attention and memory disorders correlated with central and peripheral errors and language disorders with central errors. Our data suggest that AD dysgraphia is firstly produced by a reduction of general cognitive resources and only marginally by disorders of specific spelling sub-components.