Epidemiology. 2018 Jan;29(1):151-159. doi: 10.1097/EDE.0000000000000747.
US-based studies have reported that older blacks perform worse than older whites on cognitive tests and have higher risk of Alzheimer disease dementia (AD). It is unclear whether these findings reflect differences in cognitive decline.
The Chicago Health and Aging Project followed individuals, 65+ years old (64% black, 36% white), for up to 18 years. Participants underwent triennial cognitive assessments; stratified randomized samples underwent assessments for AD. We compared black and white participants' cognitive performance, cognitive decline rate (N = 7,735), and AD incidence (N = 2,144), adjusting for age and sex.
Black participants performed worse than white participants on the cognitive tests; 441 participants developed AD. Black participants' incident AD risk was twice that of whites (RR = 1.9; 95% CI, 1.4, 2.7), with 58 excess cases/1,000 occurring among blacks (95% CI, 28, 88). Among noncarriers of APOE ε4, blacks had 2.3 times the AD risk (95% CI, 1.5, 3.6), but among carriers, race was not associated with risk (RR = 1.1; 95% CI, 0.6, 2.0; Pinteraction = 0.05). However, cognitive decline was not faster among blacks: the black-white difference in 5-year change in global cognitive score was 0.007 standard unit (95% CI, -0.034, 0.047). Years of education accounted for a sizable portion of racial disparities in cognitive level and AD risk, in analyses using a counterfactual approach.
The higher risk of AD among blacks may stem from lower level of cognitive test performance persisting throughout the observation period rather than faster rate of late-life cognitive decline. Disparities in educational attainment may contribute to these performance disparities. See video abstract at, http://links.lww.com/EDE/B299.
基于美国的研究报告称，老年黑人在认知测试中的表现逊于老年白人，并且患阿尔茨海默病痴呆症（AD）的风险更高。目前尚不清楚这些发现是否反映了认知能力下降方面的差异。
芝加哥健康与老龄化项目对年龄在 65 岁及以上的个体（64%为黑人，36%为白人）进行了长达 18 年的随访。参与者每三年接受一次认知评估；分层随机抽样样本接受 AD 评估。我们比较了黑人和白人参与者的认知表现、认知衰退率（N=7735）和 AD 发病率（N=2144），并调整了年龄和性别因素。
黑人参与者在认知测试中的表现逊于白人参与者；有 441 名参与者患有 AD。黑人参与者的 AD 发病风险是白人的两倍（RR=1.9；95%CI，1.4，2.7），黑人每 1000 人中多发生 58 例 AD（95%CI，28，88）。在不携带 APOE ε4 的人中，黑人患 AD 的风险是白人的 2.3 倍（95%CI，1.5，3.6），但在携带者中，种族与风险无关（RR=1.1；95%CI，0.6，2.0；P 交互=0.05）。然而，黑人的认知衰退速度并不快：黑人与白人之间 5 年全球认知评分变化的差异为 0.007 个标准单位（95%CI，-0.034，0.047）。在使用反事实方法进行的分析中，教育年限在认知水平和 AD 风险的种族差异中占相当大的比例。
黑人患 AD 的风险较高可能源于整个观察期内认知测试表现较低，而不是晚年认知衰退速度较快。教育程度的差异可能导致了这些表现上的差异。观看视频摘要，网址：http://links.lww.com/EDE/B299。
