Alzheimer’s disease is a devastating condition that slowly destroys memory and thinking ability, affecting millions of older adults worldwide.
For decades, scientists have focused mainly on two hallmarks of the disease: the buildup of sticky amyloid plaques and tangles of a protein called tau in the brain.
However, new research suggests that another factor may play an important role much earlier than previously thought—how blood and oxygen move through the brain.
A study from the Mark and Mary Stevens Neuroimaging and Informatics Institute at the Keck School of Medicine of USC has found that even small changes in brain blood flow and oxygen delivery may be closely linked to Alzheimer’s risk.
The research looked at older adults both with normal thinking and with signs of cognitive problems. Scientists discovered that people whose brains maintained healthier circulation tended to show fewer signs of the disease.
The brain depends on a constant supply of oxygen and nutrients carried by blood. Blood vessels act like highways delivering these essential resources to billions of brain cells. When these vessels become damaged or less flexible with age, the brain may not receive enough oxygen. Over time, this shortage can cause inflammation, weaken brain cells, and interfere with memory.
To study this process, researchers used two simple and painless techniques that do not require surgery or injections. One method used ultrasound to measure how quickly blood moves through the brain’s main arteries.
The other used light sensors placed on the scalp to evaluate how effectively oxygen reaches the brain’s surface. These tests can be done while a person rests quietly, making them far easier than traditional brain scans.
After collecting the data, scientists combined the results using advanced calculations to assess overall vascular health in the brain. They compared these measurements with common signs of Alzheimer’s, such as amyloid buildup and shrinkage of the hippocampus, a brain region essential for forming memories.
The results were striking. People whose blood flow and oxygen delivery resembled those of healthy individuals tended to have lower levels of amyloid and a larger hippocampus. Both of these features are linked to better memory and lower risk of Alzheimer’s disease.
In contrast, individuals with mild cognitive impairment or dementia showed weaker vascular function, suggesting that declining blood vessel health may be part of the disease process.
These findings add to growing evidence that Alzheimer’s is not only a disease of brain cells but also a disease of blood vessels. Poor circulation may contribute to damage long before memory problems appear. If this is true, improving vascular health through lifestyle changes or medical treatment could help protect the brain.
Another important advantage of these techniques is their simplicity. Unlike MRI or PET scans, they are less expensive and easier to perform. They do not expose patients to radiation or require injections, which means they could potentially be used to screen large numbers of people or monitor changes over time.
In reviewing the study, the findings suggest a promising new direction for early detection of Alzheimer’s disease. If doctors can identify changes in brain circulation years before symptoms appear, they may be able to intervene sooner.
However, the research shows only a snapshot in time and cannot prove that poor blood flow directly causes the disease. Long-term studies are now underway to see whether these vascular changes can predict future cognitive decline.
Overall, the study highlights how closely brain health is connected to the health of the body’s blood vessels. It suggests that protecting the heart and circulation may also protect memory and thinking abilities.
As scientists continue to explore this connection, maintaining healthy blood pressure, staying physically active, and following a balanced diet may prove to be important steps in reducing Alzheimer’s risk.
If you care about brain health, please read studies about vitamin D deficiency linked to Alzheimer’s and vascular dementia, and blood pressure problem at night may increase Alzheimer’s risk.
For more information about brain health, please see recent studies about antioxidants that could help reduce dementia risk, and epilepsy drug may help treat Alzheimer’s disease.
The study is published in Alzheimer’s & Dementia.
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