Bilingualism in Primary Progressive Aphasia: A Retrospective Study on Clinical and Language Characteristics

Abstract

Background: Primary progressive aphasia (PPA) is a neurodegenerative disorder characterized by progressive deterioration of language. Being rare, reports of PPA in multilingual individuals are scarce, despite more than half of the world population being multilingual.

Methods: We describe clinical characteristics of 33 bilingual patients with PPA, including symptom presentation and language deficits pattern in their first (L1) and second language (L2), through a systematic literature review and new cases retrospectively identified in 5 countries.

Results: In total, 14 patients presented with nonfluent/agrammatic variant, 6 with semantic variant, and 13 with logopenic variant, with a median symptom onset of 2 years. Word-finding difficulties was the first symptom in 65% of all cases, initially noticed in L2, and not always the dominant language. Our group had 22 different languages as L1, and 9 as L2. At the whole-group level there was a tendency for parallel impairment in both languages, in line with the shared bilingual neural substrate hypothesis, but each PPA variant showed some heterogeneity.

Discussion: Each PPA variant showed heterogeneity, showing the need for comprehensive language and cognitive assessment across languages, as well as further clarification on the role of language mediators.

Figures

Figure 1. Frequency of L1 and L2 languages

Figure 1 depicts the frequency of L1 (first language) and L2 languages. In total 22 including 22 different languages are represented. English was the most common first language (L1), followed by European Portuguese and Spanish. Most patients’ second language (L2) was English (n=19), and besides four French second language-speakers, other second languages included Spanish (n= 2), Italian (n=2), Hebrew (n=2), Catalan, German, Mandarin, and Japanese.