Association between hemoglobin levels and cerebral white matter volume in a general older Japanese population: the Iki-Iki study

Although previous studies have reported that hemoglobin levels can affect the brain, very few have focused on the association between hemoglobin levels and brain volume. We aimed to identify the influence of hemoglobin levels on brain volume measured using magnetic resonance imaging (MRI) in a large elderly population.

This cross-sectional study included 2153 participants (median age, 69 years; 60.2% female) who underwent 3T brain MRI. Multiple regression analyses were performed after adjusting for potential confounders. In the subgroup analyses, participants were divided into four groups according to sex and age threshold (lower age group [65–74] and higher age group [≥ 75]).

After adjusting for potential confounders, total white matter volume reduction was found to be associated with decreased hemoglobin levels (females: standardized β = 0.059, [95% confidence interval (CI): 0.0032, 0.11], P = 0.038, males: standardized β = 0.069 [95% CI: -0.00023, 0.14], P = 0.051). This relationship was notable in younger age groups of both sexes. After adjustment, the total gray matter and hippocampal volumes were not significantly associated with hemoglobin levels.

Low hemoglobin levels may have deleterious effects on white matter volume, which diminishes with age.