Study links anemia to higher dementia risk and Alzheimer’s blood biomarkers
A study of 2,282 adults aged 60 and older found anemia was associated with higher Alzheimer’s disease blood biomarkers and a 66% higher chance of developing dementia. The highest risk was seen in participants with both anemia and higher biomarker levels.
Anemia was associated with greater levels of blood biomarkers for Alzheimer’s disease and with an increased risk for dementia over time in a study of older adults. Over 16 years of follow-up, participants with anemia had a 66% higher chance of developing dementia than participants who had normal hemoglobin levels, and the highest risk was seen in those who had both anemia and higher levels of Alzheimer’s disease biomarkers.
Researchers used information from 2,282 participants in the Swedish National Study on Aging and Care in Kungsholmen. Participants were all at least sixty years old and did not have dementia at baseline. Among participants, 8.7% had baseline anemia.
Researchers looked at a number of blood biomarkers of Alzheimer’s disease from the blood samples of participants and evaluated participants for anemia using blood hemoglobin levels. Participants with anemia were more likely to be male, have more chronic diseases, have a lower education level, and be older. Participants with anemia had higher levels of Alzheimer’s disease biomarkers, and two particular biomarkers were more elevated in men than in women.
There were 16 years of follow-up, and the average follow-up time was 9.3 years. Throughout the follow-up, 15.9% of participants developed dementia. Researchers found that anemia was associated with a higher risk of developing dementia, and the higher risk remained even after excluding participants who had mild cognitive impairment and who were diagnosed with dementia within six years of follow-up.
Researchers also found the relationship between hemoglobin and higher dementia risk plateaued when hemoglobin levels reached a certain level, slightly above the definitions for anemia. When looking at sex, they found this nonlinear association was significant for men but not for women.
The risk for dementia increased as levels of Alzheimer’s disease biomarkers increased and hemoglobin levels decreased. In contrast, participants who had low levels of the biomarkers and normal hemoglobin had the lowest risk for dementia. One particular biomarker stood out: NfL. When combined with anemia, having an elevated level of this biomarker showed a risk for dementia that indicated an additive interaction. APOE-ε4 status also appeared to affect some results.
The researchers found that anemia appeared to increase risk for dementia and be linked to higher Alzheimer’s disease blood biomarkers more in men than in women, though they encouraged caution with sex-specific findings. The study also had limitations, including a risk for errors in dementia diagnoses or in information that was self-reported by participants, limited ability to explore more extreme anemia cases, and missing data on hemoglobin levels and biomarkers.