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A study tracking 316,542 South Korean adults found that people with hemoglobin levels in the lowest group—and, for some outcomes, the highest group—were more likely to later receive a dementia diagnosis. The observational results show an association, not that hemoglobin causes dementia or that changing it would prevent the disease.
A study of 316,542 South Korean adults found that hemoglobin levels recorded in routine health screenings were associated with later dementia diagnoses over as many as 15 years. The researchers say the findings may help investigate links between general physical health and brain health, but do not show that hemoglobin itself causes dementia or that changing its level can prevent it.
The participants were 40 or older and had national health screenings in 2004–2005. Researchers grouped them into five categories based on hemoglobin levels, then used national health insurance records to identify new dementia diagnoses through the end of 2019. Hemoglobin is a protein in red blood cells that carries oxygen around the body and is commonly measured in routine blood tests.
Compared with the group that had the lowest dementia rate, people in the lowest fifth of hemoglobin levels had a 16% higher risk of all-cause dementia, while those in the highest fifth had a 7% higher risk. For Alzheimer’s disease, the reported increase was concentrated in the lowest fifth, which had a 14% higher risk than the reference group.
Results varied for vascular dementia, which is associated with reduced blood flow to the brain. The lowest hemoglobin group had a 19% higher risk, while the highest group had an 18% higher risk. The relationship did not follow a simple pattern across all five groups. The researchers also reported that the association was clearer and more consistent among women than men.
A Routine Measure for Long-Term Research
Hemoglobin is already measured in standard blood tests, so a possible association with dementia could be studied using existing medical records rather than relying only on specialized scans or emerging biomarkers. The study’s size and long follow-up provide researchers with evidence to investigate how whole-body health may relate to brain health over time.
That does not make hemoglobin a validated dementia screening test. The reported differences are associations within a particular population, and the results do not establish how well a hemoglobin reading can predict an individual’s future. The study also does not show that treating an abnormal result changes dementia risk. Its immediate relevance is to research and clinical understanding, not a new prevention recommendation.
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How Researchers Tracked Dementia
The study was presented at the 39th ECNP Congress in Munich and published in the Journal of Alzheimer’s Disease, according to the report. It used a national screening cohort in South Korea and insurance records to track diagnoses, allowing researchers to compare baseline hemoglobin groups with later recorded outcomes.
Low hemoglobin is commonly associated with anemia. Unusually high levels can be linked to several factors, including smoking, dehydration, lung or heart disease, or other medical conditions. Those possibilities matter because a hemoglobin reading can reflect broader health circumstances rather than a direct process affecting the brain.
Study lead researcher Dr. Hyun Soo Kim, an assistant professor at Dong-A University College of Medicine in Busan, said the results point to hemoglobin as a possible marker of wider physical vulnerability. The research was observational: it examined patterns in existing health information rather than assigning participants to have different hemoglobin levels.
“The findings do not show that hemoglobin itself causes dementia, but suggest that abnormal hemoglobin levels may be a visible marker of wider physical vulnerability relevant to brain health.”
— Dr. Hyun Soo Kim, study lead and assistant professor at Dong-A University College of Medicine
Association Does Not Establish Cause
Because the study was observational, it cannot show that low or high hemoglobin directly causes dementia. Other health factors may help explain the association. The researchers also said that early, undiagnosed dementia processes could affect nutrition, frailty, weight loss, or anemia, potentially influencing hemoglobin before a diagnosis is recorded.
The study followed adults in South Korea, so it remains uncertain whether the same patterns apply to people from other countries and backgrounds. The report does not provide evidence that hemoglobin levels can accurately predict an individual’s risk, nor does it establish why the association appeared clearer in women or why vascular dementia results differed across hemoglobin groups.
The findings are not a recommendation to take iron, raise a low reading, or lower a high one to prevent dementia. Kim said people with an abnormal result should discuss it with a doctor, since it may point to an underlying health issue that needs attention.
Testing Results Across More Populations
Further research will need to test whether the association appears in populations beyond South Korea and clarify which health factors may account for it. Researchers will also need to determine whether hemoglobin adds useful information to existing ways of understanding dementia risk, and whether any interventions related to the underlying health conditions affect later outcomes.
For now, an abnormal hemoglobin result should be interpreted in its usual medical context, not as a dementia forecast. The study’s authors and outside commentator say more work is needed before the finding can inform risk-reduction strategies or clinical screening.
Key Questions
Does low hemoglobin cause dementia?
This study does not show that it does. It found an association between hemoglobin groups and later diagnoses, but its observational design cannot establish cause and effect.
What did the study find about high hemoglobin?
People in the highest fifth had a 7% higher risk of all-cause dementia than the reference group. For vascular dementia, the highest group had an 18% higher risk; the pattern did not rise consistently across all five groups.
Should I take iron or change my hemoglobin to prevent dementia?
No prevention benefit was tested or established. The study’s lead researcher cautioned against taking iron or trying to raise or lower hemoglobin for dementia prevention. Discuss an abnormal blood result with a doctor.
How long were participants followed?
The 316,542 adults had health screenings in 2004–2005, and researchers tracked new dementia diagnoses through the end of 2019—up to 15 years.
Source: rss
