Research Highlights
- A large U.S. study of nearly 2 million older adults found that cerebral amyloid angiopathy, a condition in which amyloid proteins build up in brain blood vessels, is linked to a much higher risk of developing dementia within five years.
- The increased dementia risk appeared consistently in people with cerebral amyloid angiopathy whether or not they had ever experienced a stroke, suggesting the condition itself plays a major role in cognitive decline.
- Researchers say the findings underscore the importance of early cognitive screening after a diagnosis of cerebral amyloid angiopathy, which could help identify memory and thinking problems sooner and slow further decline.
Protein Buildup in Brain Blood Vessels Linked to Dementia Risk
Cerebral amyloid angiopathy (CAA) is a brain disorder in which a protein called amyloid accumulates in blood vessels, gradually weakening them. A large preliminary study found that people diagnosed with CAA were about four times more likely to develop dementia within five years, whether or not they had previously experienced a stroke.
The findings will be presented at the American Stroke Association’s International Stroke Conference 2026, taking place in New Orleans from February 4-6, 2026. The conference is a leading global meeting focused on advances in stroke and brain health research.
How CAA Affects the Brain and Blood Vessels
CAA is known to increase the risk of hemorrhagic stroke (bleeding stroke) and ischemic stroke (clot-caused stroke). As part of normal aging, small amounts of amyloid can collect in the brain’s blood vessels without causing symptoms. A diagnosis of CAA is made when this buildup becomes extensive enough to damage vessels and interfere with normal brain function.
In more advanced cases, amyloid deposits can weaken vessel walls to the point where they crack. When this happens, blood can leak into surrounding brain tissue, causing a hemorrhagic stroke. Beyond stroke risk, CAA is also linked to cognitive decline and is frequently found in people with Alzheimer’s Disease. The current study examined how often dementia develops after a CAA diagnosis and how stroke and CAA together influence that risk.
Researchers Examine Dementia Progression at Scale
“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.
“Our study calculated estimates from a large sample of Medicare patients whether people with CAA are more likely to be newly diagnosed with dementia and to clarify how CAA and stroke — separately and together — relate to new dementia diagnoses.”
To answer these questions, researchers analyzed Medicare health records from more than 1.9 million adults age 65 and older between 2016 and 2022. The team focused on new dementia diagnoses and examined how both ischemic and hemorrhagic stroke affected dementia risk among people with CAA.
Patients were followed as their health status changed over time: no CAA or stroke, CAA only, stroke only, both CAA and stroke. Tracking these transitions allowed researchers to determine how long individuals remained in each category and identify when dementia was first diagnosed, Bruce explained.
Dementia Risk Was High Even Without Stroke
The analysis showed that CAA substantially raised dementia risk within the five-year window, exceeding the impact of stroke alone.
Key findings included:
- The five-year risk of a dementia diagnosis was about four times higher in people with CAA than in those without CAA (42% vs. 10%, respectively).
- People with both CAA and stroke were 4.5 times more likely to be diagnosed with dementia at any given time point compared to adults with neither condition.
- People with CAA but no history of stroke were 4.3 times more likely to receive a dementia diagnosis at any given time point compared to those with neither CAA nor stroke.
- Adults who had experienced stroke without CAA were 2.4 times more likely to be diagnosed with dementia compared to those with neither condition.
“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. This suggests that non-stroke-related mechanisms are instrumental to dementia risk in CAA,” Bruce said. “These results highlight the need to proactively screen for cognitive changes after a diagnosis of CAA and address risk factors to prevent further cognitive decline.”
Experts Say Small Vessel Disease Plays a Major Role
Steven M. Greenberg, M.D., Ph.D., FAHA, former chair of the International Stroke Conference and author of the commentary, Cerebral Amyloid Angiopathy | Stroke, emphasized the broader implications. “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. We know there is risk for dementia after any type of stroke, but these results suggest even greater risk for CAA patients.”
Greenberg, a professor of neurology at Harvard Medical School in Boston, was not involved in the study.
American Stroke Association volunteer expert Steven M. Greenberg, M.D., Ph.D., FAHA, is former chair of the International Stroke Conference and author of the commentary, Cerebral Amyloid Angiopathy | Stroke, “Diseases of the brain’s small blood vessels are major contributors to dementia and a professor of neurology at Harvard Medical School in Boston. He was not involved in this study.
Study Limitations and Next Steps
The researchers noted several limitations. The analysis relied on administrative diagnosis codes from inpatient and outpatient Medicare insurance claims rather than detailed clinical evaluations. “These codes are an imperfect proxy for clinical diagnoses, and misclassifications can occur,” Bruce said. To reduce this risk, the team used diagnosis codes that have previously shown strong accuracy in administrative data. Imaging data were not available, limiting the ability to confirm CAA and stroke diagnoses more precisely.
The authors emphasized the need for future studies that follow patients forward in time rather than relying on past records. These prospective studies should also use standardized diagnostic methods for both CAA and stroke to confirm the findings.
Study Design and Population
This retrospective analysis included inpatient and outpatient Medicare claims for 1,909,365 adults in the United States. During the study period, 752 participants (0.04%) received a diagnosis of CAA.
All participants were age 65 or older, with an average age of 73 years. Women made up 54% of the group, while 46% were men. The study population included 82.4% white adults, 7.3% black adults, and 10.3% individuals from other racial groups.
Researchers analyzed multiple years of Medicare claims data collected during routine clinical care from 2016 to 2022.
Meeting: ASA International Stroke Conference 2026
Note: The study featured in this article is a research abstract. Abstracts presented at the American Heart Association/American Stroke Association’s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.