A new study analyzing data from nearly 2 million Medicare beneficiaries reveals that cerebral amyloid angiopathy (CAA) – a condition characterized by amyloid protein accumulation in brain blood vessels – is associated with a substantially higher risk of developing dementia within five years. The findings, presented at the American Stroke Association’s International Stroke Conference 2026, indicate that individuals with CAA are about four times more likely to receive a dementia diagnosis compared to those without the condition, irrespective of whether they have experienced a stroke.
Cerebral amyloid angiopathy weakens blood vessels in the brain and can lead to both hemorrhagic and ischemic strokes. It is also commonly found in individuals with Alzheimer’s disease. The study tracked health records from 2016 to 2022 for adults aged 65 and older covered by Medicare, analyzing the incidence of new dementia diagnoses among those with CAA, stroke, both, or neither. Among the 1,909,365 participants, 752 had a CAA diagnosis.
The analysis found that the five-year dementia risk for people with CAA was 42%, compared to 10% for those without CAA. When examining the combined effects, individuals with both CAA and stroke were 4.5 times more likely to be diagnosed with dementia at any given time point than those with neither condition. Those with CAA alone had a 4.3-fold increased risk, while stroke alone raised the 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,” said study author Samuel S. Bruce, M.D., M.A., an assistant professor of neurology at Weill Cornell Medicine. “This suggests that non-stroke-related mechanisms are instrumental to dementia risk in CAA.”
The results underscore the importance of proactive cognitive screening after a CAA diagnosis. “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,” Bruce noted. The study also highlights that CAA and Alzheimer’s disease often co-occur, creating what experts describe as a “potent 1-2 punch.” 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, “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.”
Limitations of the study include its reliance on administrative diagnosis codes from Medicare claims, which may not perfectly reflect clinical diagnoses. The researchers used codes validated to accurately capture diagnoses but lacked imaging data to confirm CAA and stroke cases. Further prospective studies with standardized diagnostic approaches are needed to confirm these findings.
The study’s findings were presented as a preliminary abstract at the American Stroke Association’s International Stroke Conference 2026 and have not yet been published in a peer-reviewed journal. For more information about stroke and brain health, visit stroke.org.
