Association between rural-to-urban migration and the cognitive aging trajectories of older Chinese adults: results from a prospective cohort analysis

Background Increasingly, older Chinese adults from rural areas are moving to urban areas to live with their children who have already migrated to these areas. However, few studies have examined this pattern of migration and its effects on cognitive function. We aimed to investigate the association between domestic rural-to-urban migration and the trajectories of cognitive function in older Chinese adults, as well as the factors contributing to these association. Methods Data for this study were drawn from three waves of the China Health and Retirement Longitudinal Study. Migrants were defined as participants who had ruralhukoustatus (under China's household registration system) but resided in an urban area. Cognitive functions were measured using an adapted Chinese version of the Mini-Mental State Examination. We used multilevel linear regression models to examine the association between internal migration and cognitive function trajectories. Results The study included 3876 Chinese adults aged >= 60 years at baseline. Compared with their rural non-migrant counterparts, migrants (n = 850) had higher levels of education and reported more interactions with family. Additionally, female migrants were more likely to participate in leisure activities. All cognitive function scores declined over time, but no significant differences were observed in rates of cognitive decline between migrants and non-migrants, regardless of sex. Female migrants exhibited significantly better performance in terms of total cognition (beta = 0.77,P < .001) and mental status (beta = 0.68,P < .001) than female non-migrants, whereas no inter-group difference was observed regarding memory (beta = 0.09,P > .05). Among the male subjects, no significant differences in cognitive function levels were observed between migrants and non-migrants. A series of adjusted models revealed that psychosocial factors such as residing with children, caring for grandchildren, depression and participation in leisure activities partly explained the association between migration and cognition in women. Conclusions Rural-to-urban migration was positively associated with cognitive functions only in women. However, this pattern did not affect the rate of cognitive decline in either sex. Our findings provide directions for tailored interventions improving cognitive functions of older adults and rural non-migrating older adults, especially female non-migrants.