Negative wealth shocks in later life and subsequent cognitive function in older adults in China, England, Mexico, and the USA, 2012–18: a population-based, cross-nationally harmonised, longitudinal study

BACKGROUND: Household wealth is positively related to cognitive health outcomes in later life. However, the association between negative wealth shocks and cognitive function in later life, and whether this association might differ across countries at different levels of economic development, is unclear. We aimed to investigate whether negative wealth shocks in later life are associated with cognitive function in older adults in China, England, Mexico, and the USA, and whether this association is modified by country income level. METHODS: For this population-based, cross-nationally harmonised, longitudinal study, data were analysed from core interviews of the population-based US Health and Retirement Study (2012 and 2016) and its partner studies in China (the China Health and Retirement Longitudinal Study; 2015 and 2018), England (the English Longitudinal Study of Ageing; 2012 and 2016), and Mexico (Mexican Health and Aging Study; 2012 and 2015–16), and their respective Harmonized Cognitive Assessment Protocols (HCAPs). Negative wealth shocks over the follow-up periods of the respective cohorts were defined in two ways: an extreme loss of 75% or greater from the baseline amount of wealth, and a decline in within-population wealth quintile rank. The primary outcome was the harmonised general cognitive function (GCF) factor score, which was constructed with factor analysis on the HCAP neuropsychological assessments of memory, orientation, attention, executive function, and verbal fluency performance (mean 0; SD 1). We used sampling-weighted, multivariable-adjusted linear models to examine associations. FINDINGS: Data from 9465 participants were included in this analysis: 3796 from China, 1184 from England, 1193 from Mexico, and 3292 from the USA. The mean baseline age of participants was 68·5 (SD 5·4) years in China (49·8% women), 72·0 (7·0) years in England (54·6% women), 70·6 (6·8) years in Mexico (55·1% women), and 72·7 (7·5) years in the USA (60·4% women). A wealth loss of 75% or greater was negatively associated with subsequent cognitive function in the USA (β −0·16 SD units; 95% CI −0·29 to −0·04) and China (−0·14; −0·21 to −0·07), but not in England (−0·01; −0·24 to 0·22) or Mexico (−0·11; −0·24 to 0·03). Similarly, within-population wealth quintile rank declines were negatively associated with subsequent cognitive function in the USA (β −0·07 per quintile rank decline; 95% CI −0·11 to −0·03) and China (β −0·07; −0·09 to −0·04), but not in England (−0·05; −0·11 to 0·01) or Mexico (−0·03; −0·07 to 0·01). INTERPRETATION: The impact of wealth shocks in later life on subsequent lower level of cognitive function of older adults in China, England, Mexico, and the USA differed across macro-level socioeconomic structures. These findings suggest that government policies and social safety nets in countries with different levels of economic development might have a role in protecting older adults from adverse health effects of wealth losses in later life. FUNDING: US National Institute on Aging, US National Institutes of Health.