Study Links Cerebral Amyloid Angiopathy to Fourfold Increase in Dementia Risk Within Five Years

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, regardless of whether they had experienced a stroke.

Cerebral amyloid angiopathy is a condition where amyloid proteins accumulate in the walls of the brain's blood vessels, weakening them and increasing the risk of both hemorrhagic and ischemic strokes. The study, led by Dr. Samuel S. Bruce of Weill Cornell Medicine, analyzed administrative health claims data from 1,909,365 adults aged 65 and older from 2016 to 2022. Among this population, 752 individuals (0.04%) received a CAA diagnosis during the study period. Researchers tracked participants across different health states—no CAA or stroke, CAA only, stroke only, or both CAA and stroke—to assess the onset of dementia over time.

The analysis revealed that 42% of people with CAA were diagnosed with dementia within five years of their CAA diagnosis, compared to only 10% of those without CAA. Specifically, people with both CAA and stroke were 4.5 times more likely to be diagnosed with dementia at any given time compared to adults with neither condition. Notably, individuals with CAA without a history of stroke were 4.3 times more likely to develop dementia, while those with stroke alone 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, suggesting that non-stroke-related mechanisms significantly contribute to dementia risk in CAA patients.

These findings underscore the substantial dementia risk associated with CAA, independent of stroke. According to Dr. Steven M. Greenberg, a professor of neurology at Harvard Medical School and author of a commentary on the study published in Cerebral Amyloid Angiopathy | Stroke, diseases affecting 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 noted. He emphasized that while dementia risk is known to increase after any stroke, the results indicate an even greater risk for patients with CAA.

The study's implications point to the necessity for enhanced clinical vigilance. Bruce stated that the results "highlight the need to proactively screen for cognitive changes after a diagnosis of CAA and address risk factors to prevent further cognitive decline." However, the research has limitations, including its reliance on administrative diagnosis codes from Medicare claims, which may not perfectly capture clinical diagnoses. Researchers attempted to mitigate this by using codes validated for accuracy in administrative data, but they lacked access to imaging data for more rigorous assessment of CAA and stroke diagnoses.

As an abstract presented at a scientific meeting, the findings are considered preliminary until published in a peer-reviewed journal. Further prospective studies with standardized diagnostic approaches are needed to confirm these results. The American Stroke Association provides additional resources on stroke and brain health, including information available at www.stroke.org. The association notes that its scientific content is developed independently of funding sources, with overall financial information accessible here.