Gogi aphasia: The early description of semantic dementia in Japan

Thirty years preceding the first detailed reports of semantic dementia (SD) in western countries, Imura described a unique aphasic syndrome exhibited in Japanese patients, which he called gogi (literally, "word-meaning") aphasia. Gogi aphasia directly corresponds to the pattern of language impairments described in SD, with the additional, language-specific deficit of kanji processing. Given the importance and apparently early appearance of this symptom in gogi aphasia/SD, in the present study we examined kanji and kana processing in patients with very mild semantic dementia. Fifteen mild or very mild gogi aphasia/SD patients from the Dementia and Higher Brain Function Clinic participated in this study. Each participant's language function was evaluated using the Japanese Standard Language Test for Aphasia (SLTA), comprising 26 subtests. In all cases and across all tests, the SD patients' performance was considerable better with kana than kanji processing. This pattern was consistent across all patients and was observed even in very mild SD patients. These results are consistent with the hypothesis that the early discovery of gogi aphasia/SD in Japan depended, at least in part, on the demanding nature of the Japanese written language. We wish to introduce Western researchers to the fundamental contribution of Tsunero Imura, a Japanese neuropsychiatrist, who discovered gogi aphasia and was one of the first to describe the core symptoms of SD.