Striking loss of second language in bilingual patients with semantic dementia
Studies of bilingual or multilingual patients with neurodegenerative diseases that disrupt language like the primary progressive aphasias (PPA) may contribute valuable information on language organization in the bilingual brain and on the factors affecting language decline. There is limited literature on bilingual PPA and in particular on semantic dementia, a type of PPA with selective loss of semantic memory. We studied the nature and severity of naming and comprehension deficits across languages in bilingual patients with semantic dementia (SD).
Sixteen bilingual patients with SD and 34 bilingual age-matched controls were administered the modified Boston Naming Test and components of Cambridge Semantic Battery. The patients’ performance on picture naming and word comprehension was compared across languages and with controls. The most proficient language on self-rating was labelled as L1 and less proficient as L2.
We observed striking loss of second language (L2) in SD for both receptive and expressive language, even in patients who were premorbidly fluent in their L2. Naming and comprehension in every patient’s L2 were impaired relative to both their own first-language (L1) scores and controls’ L2 scores. Furthermore, item-specific correct responses in each patient’s L2 were a subset of their successes in L1.
A striking contrast in performance between two languages in bilingual patients with SD indicates that a bilingual’s L2 or less proficient language is more vulnerable to neurodegeneration. Our findings also support a common semantic network in the brain for the different languages of bilinguals.
KeywordsPrimary progressive aphasia Semantic dementia Bilingualism Naming Word comprehension
The authors thank all the patients and their families for participating in the study and colleagues for referrals. Some of the findings from this study have been presented at the International Neuropsychological Society (INS) meeting in London, 6–8 July 2016, at the British Neuropsychological Society (BNS) meeting in London, 1 November 2018 and the International conference on Frontotemporal dementias in Sydney, 11–14 November 2018.
This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.
Compliance with ethical standards
Conflicts of interest
On behalf of all the authors, the corresponding author states that there is no conflict of interest.
The study has been approved by the hospital ethics committee.
All patients or their caregivers and controls gave informed consent according to the Declaration of Helsinki.
- 12.Liu YC, Yip PK, Fan YM, Meguro K (2012) A potential protective effect in multilingual patients with semantic dementia: two case reports of patients speaking Taiwanese and Japanese. Acta Neurol Taiwanica 21:25–30Google Scholar
- 21.Costa AS, Jokel R, Villarejo A, Llamas-Velasco S, Domoto-Reilley K, Wojtala J, Reetz K, Machado Á (2019) Bilingualism in primary progressive aphasia: a retrospective study on clinical and language characteristics. Alzheimer Dis Assoc Disord 33:47–53. https://doi.org/10.1097/WAD.0000000000000288 CrossRefPubMedGoogle Scholar
- 23.Census India (2001). http://www.censusindia.gov.in. Accessed 31 May 2019
- 24.Ramanan S, Narayanan J, D’Souza TP, Malik KS, Ratnavalli E (2015) Total output and switching in category fluency successfully discriminates Alzheimer’s disease from Mild Cognitive Impairment, but not from frontotemporal dementia. Dement Neuropsychol 9:251–257. https://doi.org/10.1590/1980-57642015DN93000007 CrossRefPubMedPubMedCentralGoogle Scholar
- 32.Correia J, Formisano E, Valente G, Hausfeld L, Jansma Bonte M (2014) Brain-based translation: fMRI decoding of spoken words in bilinguals reveals language-independent semantic representations in anterior temporal lobe. J Neurosci 34:332–338. https://doi.org/10.1523/JNEUROSCI.1302-13.2014 CrossRefPubMedPubMedCentralGoogle Scholar
- 38.Woollams AM, Cooper-Pye E, Hodges JR, Patterson K (2008) Anomia: a doubly typical signature of semantic dementia. Neuropsychologia 46:2503–2514. https://doi.org/10.1016/j.neuropsychologia.2008.04.005 CrossRefPubMedGoogle Scholar