Background/Purpose: Although studies have documented the effects of childhood socioeconomic status (SES) on health, little is known about the pathway and the longitudinal changes of SES on cognition and its specific domains. Based on the life course theory, we examined four types of life course models—critical period, accumulation, mobility, and pathway—and their impacts on cognitive trajectories among older Americans.
Methods: We used the 1998-2016 Health and Retirement Study and selected 9,036 cognitively intact respondents aged 65 and older at the baseline. Childhood conditions included three items: parental education, paternal occupation, and childhood financial status. Adult SES was measured by respondents’ education, occupation, household income and wealth. Childhood SES and adult SES are modeled as latent variables using the above seven indicators in the pathway model. Cumulative SES was created by summing the childhood conditions, SES conditions in midlife (education and occupation) and SES conditions in old age (household income and wealth) and then grouping respondents into four categories (cumulative SES disadvantage at three points to no exposure at any point). SES mobility was measured with an index that compared changes and stability in childhood conditions and adult SES with four categories (low/high stable: stable low /high in both conditions, downward/upward: low/high childhood SES to high/low adult SES).
Latent growth curve modeling (LGCM) was used to identify the trajectories of later-life cognition (i.e., global cognitive functioning, mental status, and episodic memory), with investigations on the effect of SES in childhood (i.e., critical period), the mediating role of adulthood SES (i.e., pathway), and the impacts of changing dynamics of the life course SES (e.g., accumulation and mobility).
Results: We identified a linear decline trajectory in three cognition measures. Results indicated SES disadvantage in childhood (lower parental education, father who had a blue-collar job, and people from the low-income families) was associated with lower initial cognition. Within cognitive domains, respondents whose father had a blue-collar job had a faster decline in mental status. Adult SES mediated the relationship between childhood SES and all three cognition measures. The changing dynamics in life course SES also affected cognition trajectories. More SES disadvantages accumulated over the life course led to poor initial cognition and a faster decline in mental status, but a slower decline in episodic memory. Downward mobility accelerates older adult's cognition and mental status decline, while upward mobility had no impact on cognition and memory trajectory.
Conclusions and Implications: Childhood SES and improved SES conditions over the life course could affect later-life cognition, suggesting SES is an important and modifiable factor for cognitive health. Programs addressing socioeconomic inequality in early life and interventions that facilitate positive development in SES are promising institutional efforts to alleviate health disparities and promote healthy aging.