Bidirectional relationship between anemia and cognitive function in middle-aged and older Chinese adults: a...

The increasing prevalence of anemia and cognitive decline among middle-aged and older adults poses significant public health challenges. While most studies have examined the impact of anemia on cognition, the potential for a bidirectional relationship, where cognitive function also influences anemia risk, remains less explored, particularly via longitudinal designs and advanced modeling. Therefore, we utilized data from 4521 participants (women = 2434, men = 2087) from the initial (2011-2012) and subsequent (2015-2016) waves of the China Health and Retirement Longitudinal Study (CHARLS). We measured hemoglobin levels, global cognitive function, and other factors. Linear regression was used to analyze the association between baseline anemia status and follow-up cognitive function in participants free from low cognitive performance at baseline. Binary logistic regression was used to examine the relationship between baseline cognitive function and the risk of having anemia at follow-up in participants without anemia at baseline. Finally, a cross-lagged panel model (CLPM) was used to evaluate the longitudinal bidirectional association between anemia status and cognition. Baseline anemia status was significantly associated with lower follow-up cognitive scores, particularly among women (estimates, 95% confidence interval, - 0.83 (- 1.39, - 0.28)). Higher baseline cognitive function was associated with a lower risk of follow-up anemia among women (OR = 0.97, 95% CI (0.94-0.99)) but not among men (OR = 0.02, 95% CI (0.98-1.06)). The CLPM results confirmed a robust bidirectional relationship: baseline anemia status predicted lower follow-up cognition (β =  - 0.04), and lower baseline cognition predicted a greater risk of having anemia at follow-up (β =  - 0.02). The standardized effect size of baseline anemia status on follow-up cognitive function was greater than that of baseline cognitive function on follow-up anemia status (- 0.04 vs. - 0.02). These findings provide strong evidence for a bidirectional longitudinal association between anemia status and cognitive function in this population, suggesting that interventions targeting either condition may yield reciprocal benefits for healthy aging.