A new study examining nearly 2 million older adults in the U.S. has found that cerebral amyloid angiopathy (CAA), a condition where amyloid protein accumulates in brain blood vessels, is associated with a significantly higher risk of developing dementia within five years. The preliminary research, to be presented at the American Stroke Association's International Stroke Conference 2026 in New Orleans, indicates that individuals with CAA are about four times more likely to receive a dementia diagnosis compared to those without the condition, regardless of whether they have had a stroke.
Researchers analyzed health records of more than 1.9 million Medicare beneficiaries aged 65 and older from 2016 to 2022. They tracked newly diagnosed dementia cases and examined how CAA and stroke—both ischemic and hemorrhagic—relate to dementia risk. The study found that the five-year risk of dementia was 42% among people with CAA versus 10% among those without. Additionally, people with CAA but no stroke were 4.3 times more likely to be diagnosed with dementia at any given time, while those with both CAA and stroke had a 4.5-fold higher risk, compared to individuals with neither condition. In contrast, stroke alone increased dementia risk by 2.4 times.
“What stood out was that the risk of developing dementia among those with CAA without stroke was similar to those with CAA with stroke, and both conditions had a higher increase in the incidence of dementia when compared to participants with stroke alone,” said study author Samuel S. Bruce, M.D., M.A., assistant professor of neurology at Weill Cornell Medicine. “This suggests that non-stroke-related mechanisms are instrumental to dementia risk in CAA.” The findings emphasize the need for proactive cognitive screening after a CAA diagnosis to help prevent further decline.
Cerebral amyloid angiopathy can lead to hemorrhagic stroke and raises the risk of ischemic stroke. As people age, amyloid can accumulate in brain blood vessels without causing symptoms, but significant buildup can damage vessels and impair brain function. CAA is also commonly found in individuals with Alzheimer's disease. The study highlights that CAA often coexists with Alzheimer's, creating what experts describe as a “potent 1-2 punch” for dementia.
Steven M. Greenberg, M.D., Ph.D., FAHA, a professor of neurology at Harvard Medical School and former chair of the International Stroke Conference, commented on the findings: “Diseases of the brain’s small blood vessels are major contributors to dementia. This is especially true for CAA, which often occurs together with Alzheimer’s disease. We know there is risk for dementia after any type of stroke, but these results suggest even greater risk for CAA patients.” Greenberg was not involved in the study.
The study had limitations, including reliance on administrative diagnosis codes from Medicare claims, which may not perfectly capture clinical diagnoses. Researchers used validated codes to mitigate misclassification but lacked imaging data to confirm CAA and stroke diagnoses. Further prospective studies with standardized diagnostic approaches are needed to confirm these results.
According to the American Heart Association’s 2026 Heart Disease and Stroke Statistics, stroke is now the #4 leading cause of death in the U.S. For more information, visit stroke.org or DerrameCerebral.org. The American Stroke Association provides resources on uncommon causes of stroke.
