Importance Neighborhood-level residential segregation is implicated as a determinant for poor health outcomes in black individuals, but it is unclear whether this association extends to cognitive aging, especially in midlife.

Objective To examine the association between cumulative exposure to residential segregation during 25 years of young adulthood among black individuals and cognitive performance in midlife.

Design, Setting, and Participants The ongoing prospective cohort Coronary Artery Risk Development in Young Adults (CARDIA) Study recruited 5115 black and white participants aged 18 to 30 years from 4 field centers at the University of Alabama, Birmingham; University of Minnesota, Minneapolis; Northwestern University, Chicago, Illinois; and Kaiser Permanente, Oakland, California. Data were acquired from February 1985 to May 2011. Among the surviving CARDIA cohort, 3671 (71.8%) attended examination year 25 of the study in 2010, when cognition was measured, and 3008 (81.9%) of those completed the cognitive assessments. To account for time-varying confounding and differential censoring, marginal structural models using inverse probability weighting were applied. Data were analyzed from April 16 to July 20, 2019.

Main Outcomes and Measures Racial residential segregation was measured using the Getis-Ord G_i* statistic, and the mean cumulative exposure to segregation was calculated across 6 follow-up visits from baseline to year 25 of the study, then categorized into high, medium, and low segregation. Cognitive function was measured at year 25 of the study, using the Digit Symbol Substitution Test (DSST), Stroop color test (reverse coded), and Rey Auditory Verbal Learning Test. To facilitate comparison of estimates, z scores were calculated for all cognitive tests.

Results A total of 1568 black participants with available cognition data were included in the analysis. At baseline, participants had a mean (SD) age of 25 (4) years and consisted of 936 women (59.7%). Greater cumulative exposure to segregated neighborhoods was associated with a worse DSST z score (for high segregation, β = −0.37 [95% CI, −0.61 to −0.13]; for medium segregation, β = −0.25 [95% CI, −0.51 to 0.0002]) relative to exposure to low segregation.

Conclusions and Relevance In this cohort study, exposure to residential segregation throughout young adulthood was associated with worse processing speed among black participants as early as in midlife. This association may potentially explain black-white disparities in dementia risk at older age.

重要性 社区级别的居住隔离被认为是黑人个体健康状况不佳的决定因素，但尚不清楚这种关联是否会延伸到认知老化，尤其是在中年。

目的 研究黑人个体在 25 年青年时期累积居住隔离暴露与中年认知表现之间的关系。

设计、设置和参与者 正在进行的前瞻性队列青年冠状动脉风险发展 (CARDIA) 研究从阿拉巴马大学伯明翰分校的 4 个现场中心招募了 5115 名年龄在 18 至 30 岁的黑人和白人参与者；明尼苏达大学，明尼阿波利斯；西北大学，伊利诺伊州芝加哥；和加利福尼亚州奥克兰的 Kaiser Permanente。数据是从 1985 年 2 月到 2011 年 5 月获得的。在幸存的 CARDIA 队列中，3671 人（71.8%）参加了 2010 年研究的第 25 年的考试，当时进行了认知测量，其中 3008 人（81.9%）完成了认知评估。为了解释时变混杂和差异删失，应用了使用逆概率加权的边缘结构模型。数据分析时间为 2019 年 4 月 16 日至 7 月 20 日。

主要成果和措施 种族居住隔离是使用 Getis-Ord G _i * 统计量来衡量的，并计算从基线到研究第 25 年的 6 次随访访问的平均累积隔离暴露，然后分为高、中、和低隔离。在研究的第 25 年，使用数字符号替换测试 (DSST)、Stroop 颜色测试（反向编码）和 Rey 听觉语言学习测试测量了认知功能。为了便于比较估计值，计算了所有认知测试的z分数。

结果 共有 1568 名具有可用认知数据的黑人参与者被纳入分析。在基线时，参与者的平均 (SD) 年龄为 25 (4) 岁，包括 936 名女性 (59.7%)。对隔离社区的更大累积暴露与较差的 DSST z评分相关（对于高度隔离，β = -0.37 [95% CI，-0.61 至 -0.13]；对于中等隔离，β = -0.25 [95% CI，-0.51 0.0002]）相对于暴露于低偏析。

结论和相关性 在这项队列研究中，早在中年的黑人参与者中，整个青年时期暴露于住宅隔离与较差的处理速度有关。这种关联可能潜在地解释了老年痴呆症风险的黑白差异。