Supplementary Material for: Association of lifelong cognitive reserve with dementia and mild cognitive impairment among older adults with limited formal education: a population-based cohort study

Introduction: Early-life educational attainment contributes to cognitive reserve (CR). We investigated the associations of lifelong CR with dementia and mild cognitive impairment (MCI) among older people with limited formal education. Methods: This population-based cohort study included 2127 dementia-free participants (≥60 years; 59.4% women; 81.5% with no or elementary school) who were examined at baseline (August-December 2014) and follow-up (March-September 2018). Lifelong CR score at baseline was generated from six lifespan intellectual factors. Dementia, MCI, and their subtypes were defined according to the international criteria. Data were analyzed using Cox proportional-hazards models. Results: During the total of 8330.6 person-years of follow-up, 101 persons were diagnosed with dementia, including 74 with AD and 26 with VaD. The high (versus low) tertile of lifelong CR score was associated with multivariable-adjusted hazards ratio (95% confidence interval) of 0.28 (0.14–0.55) for dementia and 0.18 (0.07–0.48) for AD. The association between higher CR and reduced AD risk was significant in people aged 60-74 but not in those aged≥75 years (P-for-interaction=0.011). Similarly, among MCI-free people at baseline (n=1635), the high (versus low) tertile of lifelong CR score was associated with multivariable-adjusted hazard ratio of 0.51 (0.38–0.69) for MCI and 0.46 (0.33–0.64) for amnestic MCI. Lifelong CR was not related to VaD or non-amnestic MCI. Discussion: High lifelong CR is associated with reduced risks of dementia and MCI, especially AD and amnestic MCI. It highlights the importance of lifelong CR in in maintaining late-life cognitive health even among people with no or limited education.

引言：早年受教育程度有助于认知储备（cognitive reserve, CR）。本研究旨在探讨终身认知储备与低正规受教育程度老年人群痴呆及轻度认知障碍（mild cognitive impairment, MCI）的关联。方法：本项基于人群的队列研究共纳入2127名无痴呆史的参与者（年龄≥60岁；女性占比59.4%；81.5%的参与者未接受过正规教育或仅接受过小学教育），所有参与者均于基线（2014年8月—12月）及随访（2018年3月—9月）阶段接受评估。基线时的终身认知储备评分基于六项终生智力因子计算得出。痴呆、MCI及其亚型均依据国际标准进行定义。本研究采用Cox比例风险模型进行数据分析。结果：总随访时长共计8330.6人年，期间共101名参与者被确诊为痴呆，其中阿尔茨海默病（Alzheimer's Disease, AD）74例，血管性痴呆（Vascular Dementia, VaD）26例。与最低三分位组相比，终身认知储备评分最高三分位组的痴呆多变量校正后风险比（95%置信区间）为0.28（0.14~0.55），AD风险比为0.18（0.07~0.48）。较高的终身认知储备与AD风险降低的关联在60~74岁人群中具有统计学意义，但在≥75岁人群中未观察到显著关联（交互作用P=0.011）。同样，在基线时无MCI的参与者（n=1635）中，与最低三分位组相比，终身认知储备评分最高三分位组的MCI多变量校正后风险比为0.51（0.38~0.69），遗忘型MCI风险比为0.46（0.33~0.64）。终身认知储备与VaD及非遗忘型MCI无显著关联。讨论：较高的终身认知储备与痴呆及MCI风险降低相关，尤以AD及遗忘型MCI最为显著。本研究结果凸显了终身认知储备对维持老年期认知健康的重要性，即便对于未接受正规教育或受教育程度有限的人群亦是如此。