DeLuca Vincent, Voits Toms
Department of Language and Culture, The University of Tromsø, Hansine Hansens veg 18, 9019, Tromsø, Norway.
Department of Language and Culture, The University of Tromsø, Hansine Hansens veg 18, 9019, Tromsø, Norway.
Neuropsychologia. 2022 May 3;169:108191. doi: 10.1016/j.neuropsychologia.2022.108191. Epub 2022 Feb 25.
Bilingualism has been associated with increases in compensatory mechanisms to age-related neurocognitive decline thus delaying dementia symptom onset and leading to a more favorable trajectory of neurocognitive aging. However, most research to date has examined bilingualism-induced effects on neurocognition within older age ranges or young adults - with middle-aged individuals typically not being a population of interest. Furthermore, bilingualism is often treated as a dichotomous variable, despite it being a heterogeneous experience on an individual level. In the present study, we employed diffusion tensor imaging (DTI) to examine whether bilingualism, and the degree of engagement in bilingual experience, modulates the nature or rate of white matter decline associated with aging. DTI data and language history data were collected from a cohort of monolingual and bilingual individuals spanning a wide age range. Two separate analyses were run. First, generalized additive models were run on matched monolingual and bilingual samples, examining effects of age on the trajectory of white matter integrity and how bilingualism modulates this effect. This analysis revealed a significant effect of age within the monolingual group for fractional anisotropy values in the right superior longitudinal fasciculus. However, the age effect within the bilingual group was not significant, indicating a faster decline in white matter integrity within the monolingual cohort. Second, general linear models were run on the entire participant sample, examining an interaction between age and degree of bilingual engagement on white matter integrity. Results from this analysis indicate that increased engagement in bilingual language use across the lifespan correlates with a slower decline in white matter integrity with age. Together these results indicate bilingualism, and specifically degree of bilingual engagement, impacts the trajectory of age-related decline in white matter integrity across the lifespan.
双语能力与年龄相关的神经认知衰退的代偿机制增加有关，从而延迟痴呆症状的发作，并导致神经认知老化的轨迹更有利。然而，迄今为止的大多数研究都考察了双语能力对老年或年轻成年人神经认知的影响，中年个体通常不是研究关注的人群。此外，尽管双语能力在个体层面上是一种异质性体验，但它通常被视为一个二分变量。在本研究中，我们采用扩散张量成像（DTI）来检验双语能力以及双语体验的参与程度是否会调节与衰老相关的白质衰退的性质或速率。从一个年龄跨度较大的单语和双语个体队列中收集了DTI数据和语言历史数据。进行了两项独立分析。首先，对匹配的单语和双语样本运行广义相加模型，研究年龄对白质完整性轨迹的影响以及双语能力如何调节这种影响。该分析揭示了单语组中年龄对右侧上纵束分数各向异性值有显著影响。然而，双语组中的年龄效应不显著，表明单语队列中的白质完整性下降更快。其次，对整个参与者样本运行一般线性模型，研究年龄与双语参与程度对白质完整性的交互作用。该分析结果表明，一生中双语语言使用的增加与白质完整性随年龄下降的减缓相关。这些结果共同表明，双语能力，特别是双语参与程度，会影响一生中与年龄相关的白质完整性衰退轨迹。
