Direct Effect of Life-Course Socioeconomic Status on Late-Life Cognition and Cognitive Decline in the Rush Memory and Aging Project.

ABSTRACT

The role of socioeconomic status (SES) across the life course in late-life cognition is unclear. We tested the hypotheses that 1) High SES in childhood, young adulthood, midlife, and late life have independent causal effects on higher cognition level and slower cognitive decline; 2) Compared with stable low SES (referent), stable high SES has the largest estimated effect for higher cognition level and slower decline among life-course SES combinations. The Rush Memory and Aging Project enrolled 1,940 dementia-free older adults in northeastern Illinois (1997-2018). We used inverse probability-weighted marginal structural models to estimate the joint and independent effect of each life-course SES on global and domain-specific cognition. A total of 1,746 participants had, on average, 6 years of follow-up. High SES at each life-course stage starting in young adulthood had a protective estimated effect on global and domain-specific cognition intercepts. Compared with consistently low SES, consistently high SES (ß = 0.64, 95% confidence interval 0.48, 0.93) and high SES beyond childhood (ß = 0.64, 95% confidence interval 0.47, 0.83) had the largest benefit for global cognition intercepts. None of the life-course SES measures influenced rate of global or domain-specific decline. Additional understanding of life-course SES components influencing cognitive level is warranted.