Tiny brain bleeds become more common as people grow older and are linked to memory problems, stroke, and dementia.
For many years, scientists believed these small bleeds happened mainly because blood vessels became weak or damaged. A new study suggests there may be another important cause that has been overlooked.
The research was carried out by scientists at the University of California, Irvine and was published in the Journal of Neuroinflammation. The team discovered that aging red blood cells may trigger tiny brain bleeds even when blood vessels do not appear to be seriously injured.
Red blood cells normally carry oxygen from the lungs to every part of the body, including the brain. As these cells age, they become less flexible and are eventually removed from the bloodstream. The researchers wanted to learn what happens if old or damaged red blood cells remain in the brain’s smallest blood vessels.
To investigate this question, the scientists first damaged red blood cells in the laboratory so they behaved like older cells. They labeled the cells with a fluorescent marker and injected them into mice, allowing the researchers to watch where the cells traveled inside the brain.
The team found that many of the aging red blood cells became trapped inside tiny blood vessels called capillaries. These vessels are so narrow that red blood cells normally pass through them one at a time. When the damaged cells became stuck, they attracted the attention of the brain’s immune system.
Special immune cells called microglia surrounded the trapped red blood cells and removed them. During this process, tiny amounts of bleeding developed around the affected blood vessels, creating what are known as cerebral microbleeds. These small areas of bleeding can be seen on brain scans and are often found in older adults.
This finding challenges the long-held idea that cerebral microbleeds are caused only by damaged blood vessel walls. Instead, the study suggests that the buildup of aging red blood cells may also play an important role in triggering these tiny bleeds.
The discovery could help explain why cerebral microbleeds are common in people with conditions such as high blood pressure, Alzheimer’s disease, and previous strokes. Understanding exactly how these bleeds form may eventually help researchers develop treatments that protect the brain before permanent damage occurs.
The researchers now plan to study how the brain normally clears away aging red blood cells and whether problems with this process contribute to different types of stroke or other neurological diseases. They also hope to learn whether preventing red blood cells from becoming trapped could reduce brain injury.
Although this research was performed in mice and more studies in humans are needed, it provides an important new way of thinking about brain health. By revealing that aging blood cells themselves may contribute to tiny brain bleeds, the study opens new possibilities for preventing stroke, preserving memory, and protecting the aging brain.
If you care about stroke, please read studies that diets high in flavonoids could help reduce stroke risk, and MIND diet could slow down cognitive decline after stroke.
For more health information, please see recent studies about antioxidants that could help reduce the risk of dementia, and tea and coffee may help lower your risk of stroke, dementia.
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