M. Arfan Ikram
In the general population, both high and low levels of hemoglobin were linked to a greater long-term risk for dementia, including Alzheimer’s disease, data published in Neurology showed.
In addition, the researchers found that anemia was associated with a 34% increased risk for dementia and a 41% increased risk for Alzheimer’s disease.
"With around 10% of people over age 65 having anemia in the Americas and Europe and up to 45% in African and southeast Asian countries, these results could have important implications for the burden of dementia, especially as the prevalence of dementia is expected to increase threefold over the next decades, with the largest increases predicted in the countries where the anemia rate is the highest," M. Arfan Ikram, PhD, of Erasmus Medical Center in the Netherlands, said in a press release.
The researchers measured serum hemoglobin in 12,305 participants without dementia enrolled in the population-based Rotterdam Study (mean age = 64.6 years) to report the long-term association of hemoglobin levels and anemia with risk for dementia and Alzheimer’s disease. To determine the underlying substrates on brain MRI, they also examined the connection between hemoglobin and vascular brain disease, structural connectivity and global cerebral perfusion in 5,267 participants without dementia.
Over the average follow-up of 12.1 years, 745 participants had anemia and 1,520 developed dementia, of whom 1,194 had Alzheimer’s disease. Ikram and colleagues found a U-shaped association between levels and dementia (P = .005), which indicated that both low and high hemoglobin levels were tied to greater risk for developing dementia (HR for lowest vs. middle quintile = 1.29 [95% CI, 1.09-1.52]; HR for highest vs. middle quintile = 1.2 [95% CI, 1-1.44]).
Compared to no anemia, overall presence of anemia was linked to a 34% higher risk for all-cause dementia (95% CI, 11-62) and 41% higher risk for Alzheimer’s (95% CI, 15-74) AD, with the highest risk estimates for macrocytic anemia, according to the results.
The results also showed similar U-shaped associations between hemoglobin and white matter hyperintensity volume on brain MRI of patients without dementia (P = .03) and structural connectivity (P < .0001), but there was no association with presence of cortical and lacunar infarcts. In addition, hemoglobin levels inversely correlated with cerebral perfusion (P < .0001). Cerebral microbleeding was also common in participants with anemia.
"More research is needed to determine whether hemoglobin levels play a direct role in this increased risk or whether these associations can be explained by underlying issues or other vascular or metabolic changes," Ikram said in the release. – by Savannah Demko
Disclosure: The authors report no relevant financial disclosures.