Cerebral amyloid angiopathy (CAA), a condition characterized by the buildup of amyloid protein in brain blood vessels, is associated with a fourfold increase in the risk of developing dementia within five years, regardless of whether the individual has had a stroke, according to preliminary research presented at the American Stroke Association's International Stroke Conference 2026. The study, which analyzed health data from nearly 2 million Medicare beneficiaries aged 65 and older, provides the first large-scale estimates of dementia progression in CAA patients.
Researchers from Weill Cornell Medicine examined data from 2016 to 2022, tracking new dementia diagnoses in relation to CAA and stroke. Among the 752 participants diagnosed with CAA, 42% developed dementia within five years, compared to 10% of those without CAA. After adjusting for other factors, individuals with CAA alone were 4.3 times more likely to receive a dementia diagnosis at any given time point, while those with both CAA and stroke were 4.5 times more likely. In contrast, stroke alone increased dementia risk by 2.4-fold.
“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 Dr. Samuel S. Bruce, assistant professor of neurology at Weill Cornell Medicine. “This suggests that non-stroke-related mechanisms are instrumental to dementia risk in CAA.” The findings underscore the importance of proactive cognitive screening after a CAA diagnosis to address risk factors and prevent further decline.
Dr. Steven M. Greenberg, a neurology professor at Harvard Medical School and former chair of the International Stroke Conference, noted in an accompanying commentary that “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, making for a potent 1-2 punch.” He added that while dementia risk is known after any stroke, these results suggest even greater risk for CAA patients.
The study has limitations, including reliance on administrative diagnosis codes from Medicare claims, which may not perfectly capture clinical diagnoses. The 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.
The American Stroke Association notes that stroke is now the fourth leading cause of death in the U.S., according to its 2026 Heart Disease and Stroke Statistics. The association provides additional resources on uncommon causes of stroke and emphasizes the need for early diagnosis and treatment of cognitive impairment after stroke.
