SIR: Semantic dementia (SD) is a frontotemporal lobar degeneration with progressively impaired word comprehension.1 Semantic dementia seems to progressively damage the semantic system with eventual loss of semantic memory for objects as well as words. The pattern of language loss in multilingual persons can yield information about the separateness of the semantic systems in each language.
Case 1. A 71-year-old man experienced a slow, progressive loss of his ability to use and understand Spanish and German. The patient was a language teacher who had been fluent in Spanish and used it daily in his everyday work. He had normal mental status and neurological examinations except for naming and recognizing famous faces. Confrontational naming in English was decreased, and many words such as cuff, lapel, or eyelashes had no meaning to him. The patient had great difficulty understanding even common nouns in Spanish, and he was no longer able to understand any German words. On an aphasia battery, word comprehension was moderately impaired in English and severely impaired in Spanish and German. Words that were comprehended in Spanish or German were not consistently comprehended in English. His magnetic resonance imaging (MRI) studies showed anterior temporal atrophy, left greater than right.
Case 2. A 66-year-old man had a 2-year history of progressive loss of the meaning of words and inability to retrieve words. Although Spanish was his first language, he spoke English at work and knew some Polish as well. His examination was intact except for naming and recognizing famous faces. Confrontational naming in Spanish was impaired, and he could not point to a tie, cuff, buckle, or other common items in the room. He could not name pictures of items and made some semantic errors (e.g., "zero" for "circle"). His performance was worse in English than in Spanish, and his Polish was lost. If he comprehended a word in one language, he did not necessarily comprehend it in the other language. His MRI scan showed left anterior temporal atrophy.
In two multilingual patients with SD, semantic anomia was progressively more impaired in their second and third languages compared to their primary languages. Words named and comprehended in one language were not consistently named and comprehended in other languages that they knew. These findings are compatible with separate lexical semantic systems for each language.
Other data support the presence of multiple lexical semantic systems. Many bilingual aphasics recover primarily in one language, and there are reports of dissociations of languages with focal lesions.2,3 In addition, there are specific language lexicons including modality specific (spoken or written), grammar specific (nouns or verbs), and even category specific (e.g., animate versus inanimate).4,5
In conclusion, these patients could differentially access word meaning from separate languages. Compared to the first language, subsequent languages are not as strongly conceptually based, and their semantic representations may be more vulnerable to brain disease. These patients suggest impairment of separate semantic systems for different languages in SD.