Abstract:
A large study involving more than 316,000 adults has found that hemoglobin levels, a measure found in a routine blood test, may provide important clues in predicting future risk of dementia. Researchers have found that people with hemoglobin levels that are too low or too high may have a higher risk of developing dementia in the future. The discovery means that a blood test used by doctors every day may help scientists better understand the link between physical health and long-term brain degeneration.
The study analyzed health data from 316,542 adults aged 40 and older in South Korea. All participants underwent national health screenings between 2004 and 2005. Researchers divided them into five groups based on their hemoglobin levels at that time and used national health insurance records to track subsequent health status for up to 15 years, until the end of 2019.
The results of the study showed that compared with a reference group with a lower incidence of dementia, those with the lowest hemoglobin levels had a 16% higher risk of developing any type of dementia in the future; those with the highest hemoglobin levels had a 7% higher risk. The researchers also found differences in the association between hemoglobin levels and Alzheimer's disease and vascular dementia.
Hemoglobin is an important protein in red blood cells that carries oxygen from the lungs to tissues throughout the body, including the brain. Low hemoglobin levels are often associated with anemia, which can result in less oxygen being received by body tissues, while abnormally high hemoglobin levels can be associated with smoking, dehydration, and certain heart or lung diseases.
The brain is very sensitive to oxygen supply, and long-term insufficient oxygen supply may affect the normal function of nerve cells. At the same time, hemoglobin abnormalities may also reflect other underlying problems in the body, such as chronic disease, poor nutrition, or abnormal cardiorespiratory function. Therefore, the researchers believe that hemoglobin levels may not only reflect the blood's oxygen-carrying capacity, but also indirectly reveal overall physical conditions related to long-term brain health.
The study further analyzed the risks of different types of dementia. For Alzheimer's disease, the increased risk was concentrated among those with the lowest hemoglobin levels, with participants in this group having a 14% higher risk of future disease than the reference group.
Vascular dementia shows a different trend. This type of dementia is often associated with damage to the blood supply to the brain. The study found that people with the lowest hemoglobin levels had a 19% higher risk of developing vascular dementia, while those with the highest hemoglobin levels also had an 18% higher risk. However, this association did not show a stable, continuous change from low to high hemoglobin levels.
The researchers also found that the association between hemoglobin levels and dementia risk was more pronounced and consistent among women, while the association was less clear among men. This suggests that gender and other biological factors may influence the link between hemoglobin and brain health, but more research is needed to confirm.
Kim Hyun-soo, the main person in charge of the study and associate professor at Dong-A University School of Medicine in South Korea, said that the study results do not prove that abnormal hemoglobin will directly cause dementia. A more reasonable explanation is that abnormal hemoglobin levels may be an easily detectable health signal that reflects certain vulnerabilities in the body related to brain aging and cognitive decline.
The value of this study is that hemoglobin is a routine blood test indicator widely used by medical institutions around the world. It does not require expensive brain imaging scans or complex testing equipment. If this link can be further confirmed in the future, doctors may be able to use existing physical examination data to help identify people who need further attention to their long-term cognitive health.
The findings also highlight once again the close relationship between overall body health and brain health. Dementia usually does not develop suddenly in a short period of time, but may go through physiological changes for many years or even longer before symptoms such as obvious memory loss, reduced judgment ability, and impairment of daily life functions finally appear. Researchers hope that by looking for easily accessible health indicators, risk signals related to future cognitive decline can be detected earlier.
However, this study still has obvious limitations. First, it is an observational study that can only find a statistical association between hemoglobin levels and future dementia risk, but cannot prove a direct cause-and-effect relationship. Certain underlying medical conditions may affect both hemoglobin levels and brain health, so hemoglobin abnormalities may simply be a symptom of other health problems.
In addition, the research subjects are all from South Korea. Whether the research results can be applied to other countries, different ethnic groups, and people with different health conditions remains to be verified. Researchers also need to determine whether incorporating hemoglobin into existing risk assessment systems can substantially improve the accuracy of dementia predictions.
The research team specifically reminds you that you should not take iron supplements by yourself in an attempt to increase hemoglobin levels based on this study, nor should you lower high hemoglobin levels without authorization in order to prevent dementia. Abnormal hemoglobin may have multiple causes, and your doctor should combine the results of other tests to determine whether further testing or treatment is needed.
The research results were published in the Journal of Alzheimer's Disease and announced at the 39th European Society of Neuropsychopharmacology Congress. The researchers believe that large-scale studies in different countries and regions are needed in the future to further clarify the specific link between hemoglobin abnormalities and dementia, and to determine whether this indicator can be used for clinical risk prediction.
This study does not mean that hemoglobin testing during general physical examinations has become a full-fledged dementia screening tool, but it provides a direction worth paying attention to: some routine health indicators that seem unrelated to the brain may hide important information about long-term cognitive health. As research continues, future dementia risk assessments may be able to combine common blood tests, specialized blood biomarkers, and other clinical information to identify people who deserve further attention earlier, before symptoms appear.
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