Neurological and digital correlates of cognition in Older Mandarin-speaking Adults

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ABSTRACT Asian Americans are the fastest growing demographic group in the US, with Chinese now representing the third most common language spoken after English and Spanish. Diagnosis-based studies have shown reduced dementia risks among older Chinese adults in the US and China, but assessment-based studies have suggested significant under-diagnosis by 50% or more. A major problem in diagnosis is the lack of reliable tools to diagnose mild cognitive impairment (MCI) or dementia (including Alzheimer’s disease [AD]) among Chinese adults in the US: about half of Chinese neuropsychological tests were created through content- only translation without adjustment for cultural, linguistic, or neurological factors, while the remaining only have translated instructions. Because language-independent neuropsychological tests are limited in scope and resolution, detection of MCI/AD in older US Chinese adults is often delayed for early intervention, clinical trial enrollment, and initiation of disease-modifying therapies. Building on the unparalleled bilingual neurocognitive expertise at Rutgers and Stanford, we have developed new Mandarin-based neuropsychological tests accounting for cognition-related differences between Mandarin and English to mirror the National Alzheimer’s Coordinating Center assessments. These include: articulation-normalized forward digit span; articulation- and lexeme-adjusted Craft Story 21; lexeme- and frequency-adjusted word list recall; Mandarin-specific word generation tasks guided by character, phoneme/pinyin, and homonym (one character sound corresponding to multiple characters); and exposure-based Trail Making Test B. We leveraged our existing community relationships to demonstrate the feasibility and reliability of using these tools in older Mandarin speakers, and we will further expand their reliability and relationship to performance using English instruments by bilingual older adults (Aim 1); determine construct and diagnostic validity analysis accounting for imaging and plasma biomarkers of neurodegeneration (Aim 2); and determine if bilingualism mediates the effects of neurodegeneration (Aim 3). We will additionally transfer these tests onto a digital platform which can then be used by centers without Mandarin-speaking clinicians, and explore the feasibility of longitudinal neuropsychological, blood, and MRI analysis in a subset of the older Chinese adults. Through this effort, we will provide the first linguistically, culturally, and neuroanatomically appropriate cognitive tests for Mandarin speakers to enhance clinical detection of MCI/AD, enable equitable enrollment into clinical trials, reduce language-associated health disparities, and determine if bilingualism is neuroprotective among Mandarin speakers.