A preliminary study presented at the American Stroke Association’s International Stroke Conference 2026 reveals that cerebral amyloid angiopathy (CAA)—a condition characterized by amyloid protein buildup in brain blood vessels—is associated with a dramatically increased risk of dementia. Analyzing data from nearly 2 million Medicare beneficiaries aged 65 and older, researchers found that individuals diagnosed with CAA had a 42% chance of developing dementia within five years, compared to 10% among those without CAA. This represents a fourfold increase in risk, even after accounting for stroke.
“Many people with CAA develop dementia; however, so far, clinicians haven’t had clear, large-scale estimates on how often and how quickly dementia progresses in these patients,” said study author Samuel S. Bruce, M.D., M.A., an assistant professor of neurology at Weill Cornell Medicine in New York City. The study tracked health status over time using inpatient and outpatient Medicare claims from 2016 to 2022, examining the relationship between CAA, stroke, and new dementia diagnoses.
The findings highlight that CAA’s impact on dementia risk is comparable whether or not a patient has experienced a stroke. Individuals with CAA alone were 4.3 times more likely to be diagnosed with dementia at any given time point, while those with both CAA and stroke had a 4.5-fold increased risk. In contrast, stroke alone raised 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,” Bruce noted, suggesting that non-stroke mechanisms, such as direct vascular damage or coexisting Alzheimer’s pathology, are instrumental in driving cognitive decline.
Cerebral amyloid angiopathy, which can lead to hemorrhagic and ischemic strokes, is often found in individuals with Alzheimer’s disease. According to Steven M. Greenberg, M.D., Ph.D., FAHA, former chair of the International Stroke Conference and a professor of neurology at Harvard Medical School, “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.” Greenberg, who was not involved in the study, added that these results underscore the need for proactive cognitive screening after a CAA diagnosis.
The study’s limitations include reliance on administrative diagnosis codes, which may not perfectly capture clinical diagnoses, and lack of imaging data to confirm CAA or stroke. The findings are considered preliminary until published in a peer-reviewed journal. However, the large sample size—over 1.9 million adults, of whom 752 had a CAA diagnosis—provides robust evidence for the association. Researchers call for prospective studies to confirm these results and for clinicians to address risk factors to prevent further cognitive decline in CAA patients.
