A preliminary study analyzing health data from nearly 2 million U.S. adults covered by Medicare has identified a strong association between cerebral amyloid angiopathy (CAA) and a significantly increased risk of developing dementia within five years. The research, to be presented at the American Stroke Association's International Stroke Conference 2026, found that individuals diagnosed with CAA were approximately four times more likely to receive a new dementia diagnosis compared to those without the condition.
Cerebral amyloid angiopathy is a condition where amyloid proteins accumulate in the walls of the brain's blood vessels, weakening them. This buildup can lead to hemorrhagic stroke (bleeding stroke) and raises the risk of ischemic stroke (clot-caused stroke). The condition is also a known contributor to cognitive impairment and is frequently found in individuals with Alzheimer's disease. The study investigated the specific risk of dementia development among adults diagnosed with CAA, examining the relationship between CAA, stroke, and subsequent dementia diagnoses.
Researchers, led by Dr. Samuel S. Bruce of Weill Cornell Medicine, analyzed health information for more than 1.9 million adults aged 65 and older from 2016 to 2022. They tracked patients through various health states—no CAA or stroke, CAA only, stroke only, and both CAA and stroke—to observe the onset of dementia. The analysis revealed that the risk of being diagnosed with dementia within five years of a CAA diagnosis was 42% for people with CAA, compared to 10% for those without CAA.
Notably, the increased dementia risk associated with CAA appeared significant regardless of stroke history. People with CAA without stroke were 4.3 times more likely to be diagnosed with dementia at any given time compared to patients with neither condition. Those with both CAA and stroke were 4.5 times more likely, while adults with only stroke without CAA were 2.4 times more likely. "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 explained. "This suggests that non-stroke-related mechanisms are instrumental to dementia risk in CAA."
These findings underscore the importance of CAA as a major contributor to dementia risk, potentially independent of stroke. Dr. Steven M. Greenberg, a professor of neurology at Harvard Medical School and author of a commentary on the topic, noted in Cerebral Amyloid Angiopathy | Stroke that diseases of the brain's small blood vessels are significant factors in dementia. "This is especially true for CAA, which often occurs together with Alzheimer's disease, making for a potent 1-2 punch," Greenberg stated.
The study's implications are substantial for clinical practice. The researchers emphasize the necessity for healthcare providers to proactively screen for cognitive changes following a CAA diagnosis. Early detection could allow for interventions to address risk factors and potentially slow further cognitive decline. The American Stroke Association provides resources on stroke and brain health, with more information available at www.stroke.org.
Study limitations include reliance on administrative diagnosis codes from Medicare claims, which may not perfectly capture clinical diagnoses. Researchers attempted to mitigate this by using codes previously validated for accuracy. They also lacked access to imaging data for more rigorous assessment of CAA and stroke diagnoses. The findings, presented in an abstract at the conference, are considered preliminary until published as a full manuscript in a peer-reviewed journal. Further prospective studies with standardized diagnostic approaches are needed to confirm these results.
