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

Abstract

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 rural hukou status (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 (β = 0.77, P < .001) and mental status (β = 0.68, P < .001) than female non-migrants, whereas no inter-group difference was observed regarding memory (β = 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.

Association between childhood friendship and cognitive ageing trajectory in later life: evidence from the China Health and Retirement Longitudinal Study (CHARLS)

“…We obtained cognitive function data from baseline and all three follow-up assessments. In line with previous studies, cognitive function was measured by the total cognitive function score, which assesses two dimensions: episodic memory and mental intactness [ 9 , 23 , 24 ]. Episodic memory was assessed using word recall tests [ 9 , 23 , 24 ].…”

“…In line with previous studies, cognitive function was measured by the total cognitive function score, which assesses two dimensions: episodic memory and mental intactness [ 9 , 23 , 24 ]. Episodic memory was assessed using word recall tests [ 9 , 23 , 24 ]. In the word recall tests, the investigators read a list of 10 Chinese nouns to the respondents.…”

“…Identifying modifiable risk factors for cognitive ageing and impairment could inform development of healthy ageing intervention and strategies [ 4 ]. According to life course theory, early-life experiences have a far-reaching influence across the entire life span [ 5 , 6 ], which has been corroborated by previous evidence that childhood experience, such as education, family socioeconomic status, and migration at a young age, were associated with cognitive function in later life [ 7 – 9 ]. However, there is a dearth of empirical studies assessing whether and how childhood friendships affect the cognitive ageing trajectory and impairment in middle and old age.…”

“…The respondents were then asked to repeat the word list in any order immediately (immediate recall) and recall the same words 4 min later (delayed recall). The episodic memory score was calculated as the average of the immediate and delayed recall scores [ 9 , 23 , 24 ]. Scores ranged from 0 to 10, with a higher memory score indicating better episodic memory.…”

“…The total cognitive function score was the sum of the episodic memory and mental intactness scores. The scores ranged from 0 to 21, with a higher score indicating better cognitive function [ 9 , 23 , 24 ].…”