Association of Anemia with Dementia and Cognitive Decline among Community-Dwelling Elderly

Introduction: The association of anemia with dementia in elders is controversial. We examined the potential association of anemia with dementia in a large population of elders. Methods: Historical-prospective registry-based study. Included 36,951 community-dwelling elders (65-113 years) that were followed during 2002-2012. Anemia of all kinds was defined according to Clalit Health Services (CHS) definitions: hemoglobin (HGB) <14 g/dL men, <12 g/dL women; and World Health Organization (WHO): HGB <13 g/dL men, <12 g/dL women. Anemia was categorized as mild (HGB 11-13 g/dL men, 11-12 g/dL women) or moderate-severe (HGB <8-10.9 g/dL men and women). Background data, laboratory values, and diagnosis of dementia and cognitive decline (DCD) were reviewed. Results: During the 10-year follow-up period, DCD was newly diagnosed in 7,180 subjects (19.4%). Subjects with DCD had a higher rate of anemia than those without DCD. Time to development of DCD was 1.5 years shorter in those with than without anemia. On multivariate Cox regression analysis adjusted for age and sex, the hazard ratio (HR) for DCD was 1.45 (95% CI: 1.37-1.54) by CHS and 1.51 (95% CI: 1.41-1.61) WHO anemia criteria. The more severe the anemia, the greater the risk of DCD development (HGB 13-14 g/dL [men only], HR = 1.20 [95% CI: 1.09-1.32]; mild anemia, HR = 1.38 [95% CI: 1.28-1.49]; moderate-severe anemia, HR = 1.64 [CI: 1.41-1.90]). Every decrease in 1 standard deviation of HGB (1.4 g/dL) increased the DCD risk by 15%. A competing risk model has weakened the association of anemia with DCD risk. Conclusions and implications: Anemia in community-dwelling elders appears to be associated with an increased DCD risk in a dose-response manner. Application of the WHO anemia criteria in men may miss patients with mild anemia that places them at DCD risk. Further research should look at anemia as a cause of reversible dementia.