A preliminary study analyzing health data from nearly 2 million U.S. adults covered by Medicare has found that cerebral amyloid angiopathy (CAA) significantly increases the risk of developing dementia within five years. The research, to be presented at the American Stroke Association's International Stroke Conference 2026, indicates that individuals with CAA are approximately four times more likely to receive a dementia diagnosis compared to those without the condition, regardless of stroke history.
Cerebral amyloid angiopathy is characterized by the accumulation of amyloid proteins in the brain's blood vessels, which can weaken vessel walls and lead to hemorrhagic stroke (bleeding stroke) or contribute to ischemic stroke (clot-caused stroke). The condition is also associated with cognitive impairment and frequently co-occurs with Alzheimer's disease. According to the study's findings, the risk of dementia diagnosis within five years was 42% for people with CAA versus 10% for those without it.
"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. The research team analyzed health information from 1,909,365 adults aged 65 and older from 2016 to 2022, tracking patients through various health states including no CAA or stroke, CAA only, stroke only, and both conditions.
The analysis revealed that people with 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, those with CAA without stroke were 4.3 times more likely to receive a dementia diagnosis, 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, suggesting that non-stroke-related mechanisms significantly contribute to dementia risk in CAA patients.
These findings underscore the importance of proactive cognitive monitoring for individuals diagnosed with CAA. "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," Bruce emphasized. Steven M. Greenberg, M.D., Ph.D., FAHA, former chair of the International Stroke Conference, noted in his commentary, Cerebral Amyloid Angiopathy | Stroke, that "diseases of the brain's small blood vessels are major contributors to dementia," particularly when CAA co-occurs with Alzheimer's disease.
The study has limitations, including reliance on administrative diagnosis codes from Medicare claims data, which researchers acknowledge as "an imperfect proxy for clinical diagnoses." Additionally, the team lacked access to imaging data for more rigorous assessment of CAA and stroke diagnoses. The findings are considered preliminary until published in a peer-reviewed journal, as abstracts presented at American Heart Association/American Stroke Association scientific meetings are not peer-reviewed.
Further research is needed to confirm these results through prospective studies that follow patients forward in time and employ standardized diagnostic approaches for CAA and stroke. The study's implications are significant for clinical practice, emphasizing that CAA represents a substantial independent risk factor for dementia development, warranting increased vigilance in cognitive assessment for affected patients. Additional information about stroke statistics and resources can be found through the American Heart Association's stroke.org website.
