Association of social isolation and cognitive performance: a longitudinal study using a four-wave nationwide survey

Background This study aimed to examine the bidirectional relationship between social isolation and cognitive performance among Chinese middle-aged and older adults. Methods We used four waves of data from the China Health and Retirement Longitudinal Study. A latent growth model (LGM) was applied to examine the association between social isolation and cognitive performance across different characteristics. Results In the analysis, we ultimately included 9,367 participants after excluding respondents with missing key variables. Social isolation and cognitive performance showed significant differences across time. After adjusting for the confounders, there was a significant association between higher social isolation and poor cognitive performance (beta = -1.38, p < 0.001), and higher levels of social isolation resulted in a more pronounced decline in cognition over time (beta = 0.17, p < 0.001). Additionally, the path coefficient between the initial level of cognition at baseline and the slope of social isolation was - 0.07 (p < 0.001) and 0.01 (p = 0.021), respectively. For the correlation between slopes, our study found that females' cognition scores were more susceptible to social isolation (beta = - 2.78, p < 0.001). Similarly, regarding cognition scores, the influence of social isolation was greater among people with education below the primary level (beta = - 2.89, p = 0.002) or a greater number of chronic diseases (beta = - 2.56, p = 0.001). Conclusion Our findings support the bidirectional association between social isolation and cognition. Specifically, higher baseline social isolation and its rate of increase over time contribute to an intensification of cognitive decline at follow-up. Besides, poorer cognitive performance predicted higher social isolation.