Abstract
BackgroundOur objective was to characterize the relationship of anemia and hemoglobin concentrations with cross-sectional cognitive functions and changes in cognitive functions over 2 years in a large sample of Chinese middle aged and elderly.MethodsTen thousand nine hundred eighteen adults aged 45 years or older participating in the China Health and Retirement Longitudinal Study (CHARLS) were used for cross-sectional analyses and 9324 were used for longitudinal analysis. Cognitive functions were assessed by memory recall (episodic memory), mental status (TICS), and global cognitive function at baseline survey (Visit 1) and first follow-up survey (Visit 2). The lower the cognitive test score, the worse the cognitive function. Anemia was defined as hemoglobin concentrations lower than 13 g/dl for men and lower than 12 g/dl for women. Adjusted multivariate regression analyses were used to explore the relationships of different cognitive domains with anemia and hemoglobin concentration.ResultsOverall, the prevalence of anemia was 12.86% and the mean hemoglobin concentration was 14.37 ± 2.20 g/dl. After adjusting for socio-demographic and health-related covariates, the cross-sectional association between anemia and global cognitive function [β (95%CI) = − 0.49(− 0.69~ − 0.29)], episodic memory [β (95%CI) = − 0.14(− 0.23~ − 0.05)], and TICS [β (95%CI) = − 0.23(− 0.38~ − 0.08)] were significant and did not differ by gender. The hemoglobin concentration was also associated with global cognitive function among the whole sample (P < 0.05 for all). The longitudinal analyses showed global cognitive function and episodic memory were associated with anemia independent of covariates (P < 0.05 for all). Sensitivity analyses further provided significant results showing the association between anemia and cognition decline (P < 0.05).ConclusionThere was a cross-sectional and longitudinal association between anemia and accelerated decline in cognitive functions in Chinese middle-aged and elderly. This suggests that anemia and low hemoglobin concentrations are independent risk factors of cognitive decline.
Highlights
Our objective was to characterize the relationship of anemia and hemoglobin concentrations with cross-sectional cognitive functions and changes in cognitive functions over 2 years in a large sample of Chinese middle aged and elderly
The global cognitive function and episodic memory were associated with anemia consistently with stepwise adjusting for covariates among all analytical sample
Previous studies together with the present study have proved that anemia or low hemoglobin concentration were associated with poor cognitive performances
Summary
Our objective was to characterize the relationship of anemia and hemoglobin concentrations with cross-sectional cognitive functions and changes in cognitive functions over 2 years in a large sample of Chinese middle aged and elderly. Progressive decline of cognitive function is an early risk factor for dementia [5], and is the primary clinical manifestation of Alzheimer’s disease (AD) [6]. Tamura M et al found the association between anemia and cognitive decline was no longer significant after adjusting for multicovariates, such as age, race, gender, education, region, kidney function, diabetes, hypertension, hyperlipidemia, coronary heart disease, stroke, depressive symptoms, tobacco and alcohol use, health status, and C-reactive protein level in a 19,701 community-dwelling adults sample [19]. The lack of studies regarding risk of anemia and its association with cognitive functioning on large community-dwelling elderly samples, in China, was motivated this research
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