Association between hemoglobin levels and mild cognitive impairment in generally healthy European community-dwelling older adults: a 3-year prospective analysis of the DO-HEALTH trial

Background: Although numerous cross-sectional studies have examined the relationship between anemia and cognitive impairment or dementia in older adults, data from larger longitudinal studies, especially in generally healthy older adults, are limited. Objectives: To investigate the associations between baseline hemoglobin levels, anemia, and mild cognitive impairment (MCI) over 3 y in generally healthy older adults. Results: A total of 2150 participants were included in the analyses (mean age of 74.9 y; 61.7% females). Compared with the lowest quintile, participants in all higher quintiles had a significantly lower odds of MCI: 2nd = 34% lower odds of MCI [odds ratio (OR) = 0.66; 95% confidence interval (CI): 0.47, 0.93; P = 0.02], 3rd = 39% (OR = 0.61; 95% CI: 0.43, 0.86; P = 0.005), 4th = 44% (OR = 0.56; 95% CI: 0.39, 0.82; P = 0.003), and 5th = 36% (OR = 0.64; 95% CI: 0.43, 0.97; P = 0.03). For anemia, there was no association with the odds of MCI over time. Conclusions: Baseline hemoglobin levels >130 g/L were associated with reduced odds of MCI over 3 y. Although this study does not establish causality, it suggests further investigations in monitoring and managing hemoglobin levels, even in generally healthy older adults. This trial was registered at clinicaltrials.gov as NCT01745263.