Characteristics and evolution of writing impairment in Alzheimer's disease

Rapcsak et al. (Archs Neurol. 46, 65-67, 1989) proposed a hypothesis describing the evolution of agraphic impairments in dementia of the Alzheimer type (DAT): lexico-semantic disturbances at the beginning of the disease, impairments becoming more and more phonological as the dementia becomes more severe. Our study was conducted in an attempt to prove this hypothesis on the basis of an analysis of the changes observed in the agraphia impairment of patients with DAT. A writing test from dictation was proposed to 22 patients twice, with an interval of 9-12 months between the tests. The results show that within 1 year there was little change in the errors made by the patients in the writing test. The changes observed however were all found to develop within the same logical progression (as demonstrated by Correspondence Analysis). These findings made it possible to develop a general hypothesis indicating that the agraphic impairment evolves through three phases in patients with DAT. The first one is a phase of mild impairment (with a few possible phonologically plausible errors). In the second phase non-phonological spelling errors predominate, phonologically plausible errors are fewer and the errors mostly involve irregular words and non-words. The last phase involves more extreme disorders that affect all types of words. We observe many alterations due to impaired graphic motor capacity. This work would tend to confirm the hypothesis proposed by Rapcsak et al. concerning the development of agraphia, and would emphasize the importance of peripheral impairments, especially grapho-motor impairments which come in addition to the lexical and phonological impairments.