Kanji-predominant alexia in advanced Alzheimer's disease.

Objectives: Oral reading is preserved until the late stage of Alzheimer's disease (AD). However, it is unknown whether reading of kanji and kana is differentially impaired in Japanese AD patients. The purpose of this study was to examine alexic pattern in AD as related to two script systems.
Material and Methods: In 18 severe AD patients, reading performance was compared among kana characters, monographic kanji words, and kana-transcribed words. Auditory comprehension was also examined.
Results: With increased severity of dementia, kanji reading was clearly more impaired than kana reading, which was relatively unaffected. Graphic complexity and frequency of the kanji influenced the performance variously among the patients. Dissociation between kanji reading and comprehension was also noted.
Conclusion: As a result of multiple cognitive deficits, kanji reading is more impaired than kana reading in AD, but the difference is apparent only in the very late stage. Our findings suggest that kanji can be read correctly without meaning.