A large study of nearly 2 million older adults has found that cerebral amyloid angiopathy, a condition where amyloid proteins build up in brain blood vessels, sharply increases the risk of dementia. Within five years of diagnosis, people with this disorder were four times more likely to develop dementia than those without it, even absent a history of stroke. The findings, drawn from Medicare records, underscore the need for early cognitive screening in affected individuals.
Cerebral amyloid angiopathy (CAA) involves the accumulation of amyloid proteins in brain blood vessels, which can weaken them and lead to damage. This silent disorder is known to heighten risks of both hemorrhagic and ischemic strokes, as well as cognitive decline, and it often co-occurs with Alzheimer's disease. A retrospective analysis of Medicare claims from 2016 to 2022 examined 1,909,365 adults aged 65 and older, identifying 752 with CAA diagnoses.
The study revealed that within five years, dementia was diagnosed in about 42% of those with CAA, compared to 10% without the condition. Individuals with CAA but no stroke history faced a 4.3 times higher risk of dementia than those with neither issue. Those with both CAA and stroke had a 4.5 times elevated risk, while stroke alone increased it by 2.4 times. "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," said lead author Samuel S. Bruce, M.D., M.A., an assistant professor of neurology at Weill Cornell Medicine in New York City. He emphasized non-stroke mechanisms in CAA's impact on cognition.
Bruce noted, "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." The research highlights the importance of routine screening for memory and thinking changes post-CAA diagnosis to potentially slow decline.
Steven M. Greenberg, M.D., Ph.D., a neurology professor at Harvard Medical School, commented that small blood vessel diseases like CAA contribute significantly to dementia, often amplifying Alzheimer's effects. "We know there is risk for dementia after any type of stroke, but these results suggest even greater risk for CAA patients."
Limitations include reliance on administrative codes rather than clinical evaluations or imaging, which may introduce misclassifications. The findings will be presented at the American Stroke Association's International Stroke Conference 2026 in New Orleans from February 4-6.
