Multilingualism as a factor of resilience to Alzheimer's disease and related dementias in India

项目概要/摘要 到2050年，三分之二的老年痴呆症患者将生活在低收入和中等收入国家（LMIC）。作为 由于中低收入国家的死亡率继续下降，因此必须确定提供保护的因素， 对阿尔茨海默病和相关痴呆症（ADRD）的恢复力。一些研究发现，双语者在 与单语者相比，降低了ADRD风险，但其他研究没有发现双语优势的证据。 这项研究的基本原理是，先前研究的模棱两可的结果主要是由以下因素驱动的： 方法上的不一致限制了我们对双语在认知老化中的作用的理解，例如：1） 对潜在混杂因素的控制不足，限制了我们推断双语是否有直接影响的能力 认知或这些关系是否是由于环境和社会文化因素，2）有限 包括神经病理学的标志物，和3）很少注意双语者之间的组内差异， 如第二语言习得年龄、熟练程度、语言使用频率、语言数量 语言的多样性和语言家族的多样性。印度提供了一个独特的机会，研究双语在 鉴于全国各地丰富的语言和社会文化多样性，这是一种认知储备和复原力。整体 这项研究的目的是利用印度语言和社会人口景观的独特特征， 辨别双语是否改变了血液和神经成像生物标志物之间的关联， ADRD与认知和认知下降。这项研究将分析可用的基于血浆的淀粉样蛋白测量方法， 来自印度纵向衰老研究的tau病理学、MRI和认知评估-诊断 痴呆症评估（LASI-DAD）是一项关于印度老龄化和痴呆症的大型人口代表性研究。 具体来说，该项目将1）确定双语是否改变ADRD之间的关联 生物标志物（基于血液或神经影像学）和认知结果，2）评估是否有保护作用， 双语在不同的生命过程中的健康环境决定因素不同，3）解构语言 在印度的双语者中使用，以了解双语赋予认知储备的机制 ADRD的生物学风险。我们假设双语会缓冲血液AD生物标志物的影响， （淀粉样蛋白和tau血浆水平）、皮质萎缩和白色物质完整性对基线认知和比率的影响 在记忆、语言和执行功能方面，与单语者相比，认知能力下降。在 此外，通过对双语现象的解构，我们假设，二语习得年龄越早，双语水平越高， 熟练程度，更多的日常多种语言使用，更多的语言获得，更大的距离 语言家族之间的差异将赋予认知储备，独立于混杂的社会文化因素（即， 社会经济地位）。该提案将通过揭示潜在的 ADRD的恢复机制可能是可改变的，并可转移到其他人群。

Project Summary/Abstract By 2050, two-thirds of older individuals with dementia will live in low-and middle-income countries (LMICs). As LMICs continue to experience a reduction in mortality, it is critical to determine factors that confer protection and resilience toward Alzheimer’s disease and related dementias (ADRD). Some studies find that bilinguals are at reduced ADRD risk compared to monolinguals, but other studies do not find evidence of a bilingual advantage. The rationale for this study is that the equivocal findings of prior research has been driven largely by methodological inconsistencies that limit our understanding of bilingualism’s role in cognitive aging such as: 1) inadequate control for potential confounders that limit our ability to infer whether bilingualism has a direct effect on cognition or whether these relationships are due to environmental and sociocultural factors, 2) limited inclusion of markers of neuropathology, and 3) little attention given to within-group differences among bilinguals, such as age of second language (L2) acquisition, proficiency, frequency of language use, number of languages spoken, and diversity of language families. India offers a unique opportunity to study the role of bilingualism in cognitive reserve and resilience, given its rich linguistic and sociocultural diversity across the country. The overall aim of the study is to leverage the unique features of India’s linguistic and sociodemographic landscape to discern whether bilingualism modifies the association between blood-based and neuroimaging biomarkers of ADRD and cognition and cognitive decline. This study will analyze available plasma-based measures of amyloid and tau pathologies, MRI, and cognitive assessments from the Longitudinal Aging Study in India–Diagnostic Assessment of Dementia (LASI-DAD), a large, population-representative study of ageing and dementia in India. Specifically, the project will 1) determine whether bilingualism modifies the association between ADRD biomarkers (blood-based or neuroimaging) and cognitive outcomes, 2) evaluate whether the protective effect of bilingualism differs across diverse life-course environmental determinants of health, and 3) deconstruct language use within bilinguals in India to understand the mechanisms by which bilingualism confers cognitive reserve against biological risk of ADRD. We hypothesize that bilingualism will buffer the effects of blood AD-biomarkers (amyloid, and tau plasma levels), cortical atrophy, and white matter integrity on baseline cognition and rate of cognitive decline compared to monolinguals in the domains of memory, language, and executive functioning. In addition, by deconstructing bilingualism, we hypothesize that earlier age of L2 acquisition, higher bilingual proficiency, greater daily multiple language use, higher number of languages acquired, and greater distance between language families will confer cognitive reserve, independent of confounding sociocultural factors (i.e., education, socioeconomic status). This proposal will enhance the field of ADRD by uncovering the underlying mechanisms of resilience to ADRD that may be modifiable and transferable to other populations.