Language deterioration in four Japanese–Portuguese bilingual patients with Alzheimer's disease: a trans‐cultural study of Japanese elderly immigrants in Brazil

要旨

Abstract Background: Bilingualism is an area of linguistics that has been investigated in aphasic patients. However, bilingualism and Alzheimer's disease (AD) have not been fully investigated despite the fact that language impairment is a frequent symptom of AD. Brazil has the greatest number of Japanese immigrants and, consequently, there are many bilingual people who are fluent in both Japanese and Portuguese in Brazil. Methods: Using the results from a previous epidemiological survey, we found four AD patients who were fluent in both Japanese and Portuguese before developing AD, and performed the following evaluations in both languages: confrontation naming, oral reading ability, vocabulary comprehension (matching words and drawings), written lexical decision and the Western Aphasia Battery (WAB). Results: All patients demonstrated impaired naming ability in both languages. Oral reading ability was most impaired in the case of Kanji, followed by irregular words in Portuguese. The patients could recognize and pronounce Kana perfectly, and regular Portuguese words almost perfectly. In the severest case, the patient showed disturbed lexical comprehension and lexical decision, especially when faced with Kanji. The WAB classified three patients as having anomic aphasia in both languages, whereas in the severest case the patient was classified as having anomic aphasia in Portuguese and Wernicke aphasia in Japanese. Conclusion: These results may reflect different patterns in language deterioration as AD progresses, with Kanji being more readily affected by the disease than Kana and Portuguese. This is the first study to focus on Japanese–Portuguese bilingualism in AD patients.

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