Contribution of Life-Course Socioeconomic Position to Later-Life Brain Volumes in US Hispanic/Latino Adults.

Abstract

Low life-course socioeconomic position (SEP) has been associated with worse cognitive function in older age. However, its association with brain structure remains unclear. We assessed whether SEP at 3 periods of the life-course and socioeconomic mobility are associated with later-life MRI-derived brain volumes. We used longitudinal data from the Hispanic Community Health Study/Study of Latinos and its Investigations of Neurocognitive Aging-MRI ancillary study. We determined childhood SEP using participant self-reports of their parent's educational attainment (<high school vs ≥high school). We used indexes combining participant's education, employment, household income, and assets to determine adult SEP at visits 1 (2008-2011) and 2 (2014-2017). Using childhood and adult SEP at visit 1, we classified participants into 4 socioeconomic mobility categories (stable low or high SEP, upward or downward mobility). We also used the discrepancy between attained height and genetically predicted height (e.g., height residuals) as a biomarker of childhood environment. A higher residual would indicate a more favorable environment for growth and development. Using 3T MRI scans, we quantified (2018-2022) brain volumes (e.g., total brain volume, total gray matter volume [TGMV], total cortical gray volume, hippocampal volume, and white matter hyperintensity volume [WMHV]). We fitted linear marginal structural models accounting for the complex sampling design and covariates to quantify the association between life-course SEP and <i>z</i>-scored brain volumes. We included 2,400 adults aged 50-85 years. Higher childhood SEP (TGMV 0.13; 95% CI 0.02-0.24) and higher height residuals (TGMV 0.17; 95% CI 0.09-0.24) were associated with larger brain volumes. Similarly, higher adult SEP at visit 1 (TGMV 0.18; 95% CI 0.05-0.31) and visit 2 (TGMV 0.16; 95% CI 0.04-0.29), upward socioeconomic mobility, and stable high SEP were associated with larger brain volumes. Higher adult SEP at visit 2 (log-WMHV -0.16; 95% CI -0.29 to -0.02) and upward mobility were also associated with smaller log-WMHV. This study highlights the contribution of higher life-course SEP to greater brain health as indexed by larger brain volumes in later life. Our results suggest that the effect of early-life socioeconomic disadvantages persists beyond socioeconomic conditions in adulthood.