Life course socioeconomic determinants of multimorbidity in later life: longitudinal evidence from the Health and Retirement Study.

Using data from the Health and Retirement Study, we examined (a) how childhood socioeconomic status (SES) affects multimorbidity in later life; (b) whether the association between childhood SES and later-life multimorbidity provided empirical support for the critical period model, the sensitive period model, the pathway model and the accumulation model; (c) whether there were cohort differences in the association between childhood SES and later-life multimorbidity. Participants (N = 12,601) were grouped into three birth cohorts (1929-38, 1939-45 and post-1945) and followed up from 1998 to 2020. We performed two-level Poisson growth curve models. We found that the association between childhood SES and later-life multimorbidity was modified by SES in adulthood or older age but remained significant, supporting the sensitive period model. Childhood SES affects later-life multimorbidity via SES attainment in adulthood and older age, supporting the pathway model. Persistent disadvantage in childhood, adulthood and older age is a strong risk factor for later-life multimorbidity, supporting the accumulation model. Our results did not support the critical period model. These findings hold among all three cohorts, although to a different extent. Our findings highlight that childhood is a sensitive and malleable period in the life course of an individual when it is possible to break the chain of risk and prevent accumulation of socioeconomic disadvantage in multimorbidity in older age. Moreover, individual lives are embedded in historical and social contexts, the dynamic interplay between which plays a key role in determining the risk of multimorbidity in later life.