Scientists are discovering that Alzheimer’s disease may begin long before memory loss becomes noticeable, and the earliest warning signs may involve changes in blood flow and oxygen in the brain.
A new study from the Mark and Mary Stevens Neuroimaging and Informatics Institute at the University of Southern California suggests that how well blood circulates through the brain could reveal who is at risk for the disease years in advance.
Alzheimer’s disease is the most common cause of dementia, affecting millions of older adults worldwide. It slowly damages memory, thinking, and the ability to carry out everyday tasks.
For decades, research has focused on harmful protein buildups in the brain, especially amyloid plaques and tau tangles, as the main causes of the disease. However, scientists are increasingly realizing that the health of blood vessels may also play a key role.
In the new study, published in the journal Alzheimer’s and Dementia, researchers examined older adults with and without memory problems.
They found that subtle differences in brain blood flow and oxygen use were closely linked to known warning signs of Alzheimer’s, such as amyloid buildup and shrinkage of the hippocampus, a brain area essential for memory.
The hippocampus is one of the first regions affected by Alzheimer’s. As it shrinks, people begin to experience forgetfulness and confusion. Detecting changes before this damage becomes severe could help doctors intervene earlier and possibly slow the disease.
To measure brain blood flow and oxygen levels, the researchers used two noninvasive methods that are simple and safe. One method used ultrasound to measure how quickly blood moves through major brain arteries.
The other used a light-based technique placed on the head to estimate how much oxygen reaches brain tissue. Both tests can be done while a person sits quietly, without injections or radiation.
The scientists then analyzed the data using advanced computer models to see how well the brain adjusts blood flow in response to natural changes in blood pressure and breathing. A healthy brain can quickly regulate blood supply to maintain stable oxygen levels. When this system weakens, brain cells may not get the nutrients they need.
The results showed that people whose brain blood vessels functioned more like those of healthy older adults had lower levels of amyloid plaques and larger hippocampal volume. Both findings are associated with a lower risk of Alzheimer’s disease. In contrast, people with mild cognitive impairment or dementia showed poorer blood flow regulation.
These findings suggest that problems with blood circulation may be part of the disease process, not just a side effect. In other words, Alzheimer’s may involve both nerve cell damage and vascular problems working together.
The study is important because the testing methods are much cheaper and easier than traditional brain scans such as MRI or PET imaging. They do not require contrast dyes or exposure to radiation, making them suitable for large screening programs or for people who cannot undergo more complex tests.
However, the researchers caution that the study only shows a connection and does not prove that poor blood flow causes Alzheimer’s. Long-term studies are already underway to see whether changes in brain circulation can predict future memory decline.
In reviewing the findings, the research adds to growing evidence that maintaining good cardiovascular health may also protect brain health.
Conditions such as high blood pressure, diabetes, and smoking damage blood vessels throughout the body, including those in the brain. Managing these conditions through healthy lifestyle choices could reduce the risk of dementia.
While more research is needed, the study offers hope that simple, noninvasive tests could one day help identify people at risk long before symptoms appear. Early detection could allow treatments and lifestyle changes to begin sooner, potentially delaying or preventing the onset of Alzheimer’s disease.
If you care about Alzheimer’s disease, please read studies about the protective power of dietary antioxidants against Alzheimer’s, and eating habits linked to higher Alzheimer’s risk.
For more health information, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
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