Mediation pathways explaining racial/ethnic and socioeconomic (SES) disparities in structural MRI markers of brain health remain underexplored. We examined racial/ethnic and SES disparities in sMRI markers and tested total, direct, and indirect effects through lifestyle, health-related, and cognition factors using a structural equations modeling approach among 36,184 UK Biobank participants aged 40–70 years at baseline assessment (47% men). Race (non-White vs. White) and lower SES-predicted poorer brain sMRI volumetric outcomes at follow-up, with racial/ethnic disparities in sMRI outcomes involving multiple pathways and SES playing a central role in those pathways. Mediational patterns differed across outcomes, with the SES-sMRI total effect being partially mediated for all outcomes. Over 20% of the total effect (TE) of race/ethnicity on WMH was explained by the indirect effect (IE), by a combination of different pathways going through SES, lifestyle, health-related, and cognition factors. This is in contrast to < 10% for total brain, gray matter (GM), white matter (WM), and frontal GM left/right. Another significant finding is that around 57% of the total effect for SES and the normalized white matter hyperintensity (WMH) was attributed to an indirect effect. This effect encompasses many pathways that involve lifestyle, health-related, and cognitive aspects. Aside from WMH, the percent of TE of SES mediated through various pathways ranged from ~ 5% for WM to > 15% up to 36% for most of the remaining sMRI outcomes, which are composed mainly of GM phenotypes. Race and SES were important determinants of brain volumetric outcomes, with partial mediation of racial/ethnic disparities through SES, lifestyle, health-related, and cognition factors.

解释大脑健康结构 MRI 标志物的种族/民族和社会经济 （SES） 差异的中介途径仍未得到充分探索。我们检查了 sMRI 标志物的种族/民族和 SES 差异，并使用结构方程建模方法在基线评估时对 36,184 名年龄在 40-70 岁的英国生物样本库参与者 （47% 男性） 中测试了通过生活方式、健康相关和认知因素的总体、直接和间接影响。种族 （非白人 vs. 白人） 和较低的 SES 预测的随访时较差的脑 sMRI 体积结果，sMRI 结果的种族/民族差异涉及多种途径，SES 在这些途径中起着核心作用。不同结局的中介模式不同，SES-sMRI 总效应在所有结局中都是部分介导的。超过 20% 的种族/民族对 WMH 的总效应 （TE） 是由间接效应 （IE） 解释的，这是通过通过 SES、生活方式、健康相关和认知因素的不同途径的组合。这与总脑、灰质 （GM）、白质 （WM） 和额叶左/右 GM 的 < 10% 形成鲜明对比。另一个重要的发现是，大约 57% 的 SES 总效应和标准化白质高信号 （WMH） 归因于间接效应。这种影响包括许多涉及生活方式、健康相关和认知方面的途径。除了 WMH 之外，通过各种途径介导的 SES 的 TE 百分比从 WM 的 ~ 5% 到 > 15% 到 36% 不等，对于大多数剩余的 sMRI 结果，这些结果主要由 GM 表型组成。种族和 SES 是脑体积结局的重要决定因素，通过 SES 、生活方式、健康相关和认知因素部分介导种族/民族差异。