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A study tracking 316,542 South Korean adults found that people with very low hemoglobin, and in some analyses very high hemoglobin, were more likely to be diagnosed with dementia over as long as 15 years. The observational findings do not show that hemoglobin causes dementia or that changing its level prevents it.
A study of 316,542 South Korean adults found that hemoglobin levels recorded in routine health screenings were associated with the likelihood of a later dementia diagnosis, offering a possible clue for research into long-term brain health. The results do not establish that hemoglobin causes dementia or that changing its level would prevent the condition.
The research followed adults aged 40 and older who had a national health screening in 2004–2005. Researchers used health insurance records to identify new dementia diagnoses through the end of 2019, allowing for up to 15 years of follow-up. Participants were divided into five groups according to their hemoglobin levels, from the lowest fifth to the highest fifth.
Compared with the group that had the lowest dementia rate, people in the lowest hemoglobin group had a 16% higher risk of all-cause dementia. Those in the highest group had a 7% higher risk. These percentages describe relative differences reported by the researchers; they do not give an individual’s absolute likelihood of developing dementia.
Results varied by dementia type. For Alzheimer’s disease, the reported increase was concentrated among people in the lowest hemoglobin group, whose risk was 14% higher than the reference group. For vascular dementia, the lowest group had a 19% higher risk and the highest group an 18% higher risk; the pattern across all five groups was not straightforward. The association was clearer and more consistent in women than in men, the researchers said.
What Routine Blood Counts Could Reveal
Hemoglobin is the oxygen-carrying protein in red blood cells and is measured in many standard blood tests. Because the test is already widely used, a connection with later dementia could help researchers examine how general physical health relates to brain health, without relying only on specialist scans or newer biomarkers.
The findings are an association, not a screening recommendation. The study does not show that a hemoglobin result can predict whether a particular person will develop dementia, nor that treating an unusual result will lower dementia risk. Its potential value is in prompting further research into long-term patterns and the health factors that may influence both blood measures and brain outcomes.
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How Hemoglobin Was Tracked
Hemoglobin levels can fall in anemia and may be unusually high for a range of reasons. The report notes possible links to smoking, dehydration, lung or heart disease, and other medical conditions. A test result therefore reflects a measure with many possible influences, rather than a dementia-specific marker.
The study was presented at the 39th ECNP Congress in Munich and published in the Journal of Alzheimer’s Disease. Its large cohort and extended record-based follow-up allowed researchers to compare dementia diagnoses across hemoglobin groups over time. However, the participants were Korean adults who received screenings in 2004–2005; whether the same relationships hold in people from other backgrounds remains an open question.
“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, lead researcher and assistant professor at Dong-A University College of Medicine
Association Does Not Show Cause
Because the research was observational, it can show that hemoglobin levels and later diagnoses occurred together, but it cannot establish that one caused the other. Other health conditions or factors could contribute to both. The researchers also raised the possibility that early, undiagnosed dementia processes might affect nutrition, frailty, weight loss or anemia, influencing hemoglobin before a formal diagnosis.
The report does not establish why the association differed by dementia type or appeared more consistent in women. Nor does it show that the findings apply to populations outside the South Korean cohort. The percentages are relative risk comparisons; the supplied findings do not provide absolute risk estimates for individuals or a clinical threshold for dementia screening.
Research Needed Before Clinical Use
Further studies will need to test whether the observed association appears in people from a wider range of backgrounds and to examine what may explain the patterns across hemoglobin groups, sex and dementia types. Researchers would also need to determine whether hemoglobin adds useful information beyond other health measures before it could have a defined role in dementia risk assessment.
For now, the study’s authors advise against using iron supplements or trying to raise or lower hemoglobin to prevent dementia. Anyone with an abnormal blood test should discuss it with a qualified health professional, who can assess possible causes and appropriate care; the study does not provide medical advice for changing treatment.
Key Questions
What did the study find?
In a cohort of 316,542 South Korean adults, the lowest hemoglobin group had a 16% higher relative risk of all-cause dementia than the reference group. The highest group had a 7% higher risk. Associations differed by dementia type.
Does low hemoglobin cause dementia?
The study does not show that low or high hemoglobin causes dementia. It was observational and identified an association, which could reflect other health factors or, potentially, early changes related to dementia.
Should people change their hemoglobin to lower dementia risk?
No such benefit was established. The lead researcher cautioned against taking iron or trying to raise or lower hemoglobin for dementia prevention. Discuss an abnormal result with a qualified health professional.
Can a routine blood test predict an individual’s dementia risk?
The findings do not establish that hemoglobin can predict whether an individual will develop dementia. The study compared groups and did not establish a clinical prediction tool or screening threshold.
Do the findings apply to everyone?
That is not yet clear. The study involved South Korean adults screened in 2004–2005, and an outside expert said more research is needed to assess whether the association is present across wider backgrounds.
Source: rss
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