Bilingualism Delays Expression of Alzheimer’s Clinical Syndrome

Abstract

Objective: To evaluate the effects of bilingualism on the emergence of Alzheimer's clinical syndrome. Background: Studies have proposed an increase in cognitive and neural reserve from the management and control of two languages, with a consequent delayed expression of dementia. Methods: In a clinic with a large immigrant population, we identified 253 patients with probable Alzheimer's disease (AD) with intermediate or high evidence of AD pathophysiological process. These patients were reviewed for demographic variables, native language (L1) other than English, ages of onset and presentation, Mini-Mental State Examination (MMSE), digit spans, word fluencies, naming, and memory. Results: Among these patients, 74 (29.2%) were bilinguals with various L1s (Farsi, Spanish, Chinese, Tagalog, Arabic, others). When compared to the 179 monolingual AD patients, those who were bilingual had significant delays in ages of onset and presentation of approximately 4 years (p = 0.003). These delays persisted despite bilinguals having worse MMSE scores on presentation. There were no significant group differences on other variables except for worse naming in English among bilinguals versus monolinguals. Caregiver/informants reported that 66 (89.2%) of the 74 bilingual AD patients had gradually regressed to the predominant use of their L1. Conclusions: In line with published reports worldwide, we found that bilingualism delays the expression of Alzheimer's clinical syndrome. We also found frequent reversion to the first learned language. These findings suggest that, among bilinguals, the availability of an L1 "back-up" either facilitates compensation or masks emergence of the early symptoms of dementia.

Lifelong Bilingualism Functions as an Alternative Intervention for Cognitive Reserve Against Alzheimer's Disease

“…Bilingualism seems to have an impact on cognitive functioning at all ages (71). Importantly, L2 acquisition might be a factor promoting compensatory reserve and delaying cognitive decline in dementia (72). Individuals intensively learning L2 over 3 months show a significant increase in hippocampus volume and cortical thickness in the left middle frontal gyrus, inferior frontal gyrus, and superior temporal gyrus (73).…”

Bilingualism and Aging: Implications for (Delaying) Neurocognitive Decline

“…Other recent retrospective studies provide corroborative evidence: for instance, Zheng et al (2018) found a 7-year delay of AD onset in Cantonese/Mandarin bilingual older adults as compared to Cantonese and Mandarin monolingual peers. Finally, a study by Mendez et al (2019) replicated the finding of a 4-year AD delay in a sample of bilingual seniors who spoke various first languages (L1s) and English as a second language (L2).…”

Cognitive and brain reserve in bilinguals: field overview and explanatory mechanisms

“…Consistently with previous literature, clinical manifestation of AD appeared to be delayed by 4.6 years in bilingual patients. More recent studies confirmed bilingualism's effect on the delay of AD onset: Zheng et al (2018) reported a 7-year delay in Cantonese/Mandarin bilinguals as compared to both Cantonese and Mandarin monolinguals, while Mendez et al (2020) reported a 4-year delay in a sample of bilinguals with different L1s and English as an L2. Moreover, Perquin et al (2013) examined 232 senior multilinguals in Luxembourg who were either classified as healthy or affected by mild cognitive impairment (MCI).…”