Dementia is often thought of as a disease that slowly develops only because of problems inside brain cells. However, growing evidence shows that damage to the brain’s blood vessels also plays a major role.
A large new study suggests that a condition called cerebral amyloid angiopathy, or CAA, may sharply increase the risk of developing dementia, even in people who have never had a stroke. The findings add to concerns that silent damage in the brain can quietly progress for years before memory problems become obvious.
CAA is a disorder in which a protein called amyloid builds up inside the walls of blood vessels in the brain. Amyloid is better known for its role in Alzheimer’s disease, where it forms plaques between brain cells. In CAA, the protein collects in blood vessels instead.
Over time, this buildup weakens the vessel walls and interferes with normal blood flow. Small amounts of amyloid can appear in blood vessels as part of normal aging, but when the buildup becomes extensive, it can cause serious damage.
Doctors usually diagnose CAA when imaging scans or symptoms suggest that amyloid deposits are harming brain blood vessels. In advanced cases, the vessel walls can become so fragile that they crack and bleed.
This can lead to hemorrhagic stroke, which is caused by bleeding in the brain. CAA is also linked to ischemic stroke, which occurs when a blood clot blocks blood flow. Even without a major stroke, weakened blood vessels can slowly injure surrounding brain tissue.
The new research focused on how often people with CAA go on to develop dementia and how stroke affects that risk. The study will be presented at the American Stroke Association’s International Stroke Conference 2026, a major global meeting for scientists and doctors studying brain health and stroke.
Researchers analyzed health records from more than 1.9 million Medicare beneficiaries in the United States who were 65 years or older. The records covered the years from 2016 to 2022. By reviewing these data, the team tracked when people were diagnosed with CAA, when they experienced stroke, and when dementia was first identified.
This approach allowed researchers to see how dementia risk changed over time as people moved between different health states, such as having no disease, having CAA alone, having stroke alone, or having both.
The results were striking. Within five years, about 42 percent of people diagnosed with CAA developed dementia. In contrast, only about 10 percent of people without CAA were diagnosed with dementia over the same period. When the researchers compared different groups, they found that CAA had a stronger link to dementia than stroke alone.
People who had both CAA and a history of stroke were about 4.5 times more likely to be diagnosed with dementia at any given point than people with neither condition. Even more notable, people with CAA but no history of stroke were about 4.3 times more likely to develop dementia.
By comparison, people who had experienced stroke but did not have CAA were about 2.4 times more likely to develop dementia. This suggests that CAA itself, not just stroke-related damage, plays a major role in driving cognitive decline.
According to the study’s lead author, Dr. Samuel S. Bruce of Weill Cornell Medicine, the similar dementia risk seen in people with CAA both with and without stroke points to hidden processes at work.
The findings suggest that damage from CAA may impair brain function through mechanisms beyond obvious strokes, such as chronic injury to small blood vessels and reduced oxygen delivery to brain tissue.
Experts not involved in the research say the findings fit with a broader understanding of dementia. Diseases that affect small blood vessels in the brain are now recognized as major contributors to memory loss and cognitive decline.
CAA often occurs alongside Alzheimer’s disease, creating a powerful combination that damages both brain cells and the vessels that support them.
The researchers also acknowledged important limits to the study. The analysis relied on insurance diagnosis codes rather than detailed medical exams or brain scans. While these codes are commonly used in research and have been shown to be fairly accurate, they can still miss or misclassify cases.
The study also lacked imaging data, which would allow more precise confirmation of CAA and stroke. Future studies that follow patients forward in time with standardized testing and imaging will be needed to confirm and refine these results.
When reviewing and analyzing the findings, the main message is that CAA appears to be a strong and independent risk factor for dementia. The fact that dementia risk was nearly as high in people with CAA who never had a stroke highlights how dangerous silent blood vessel damage can be.
These results suggest that doctors should closely monitor thinking and memory in patients diagnosed with CAA, even if they seem otherwise stable. Early detection of cognitive changes may allow steps to slow decline or manage risk factors such as blood pressure.
While more research is needed, this large study strengthens the case that protecting brain blood vessels is just as important as protecting brain cells when it comes to preventing dementia.
If you care about brain health ,please read studies about Vitamin B9 deficiency linked to higher dementia risk, and cranberries could help boost memory.
For more health information, please see recent studies about heartburn drugs that could increase risk of dementia, and results showing this MIND diet may protect your cognitive function, prevent dementia.
Copyright © 2026 Knowridge Science Report. All rights reserved.
