Hidden brain condition may quadruple dementia risk in older adults, study suggests

A little-known brain blood vessel disorder could quadruple the risk of dementia in older adults, according to a preliminary study from the American Heart Association.

Cerebral amyloid angiopathy (CAA) is a condition in which protein builds up in the brain and weakens blood vessels. 

As people age, some of these proteins can collect in the brain’s blood vessels with few to no symptoms, according to the association. 

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When the buildup begins to affect brain function, doctors may diagnose the condition, typically through MRI or PET scans. In severe cases, CAA can result in a stroke.

Approximately 23% to 29% of people above the age of 50 have moderate to severe CAA, according to Cleveland Clinic.

In the new study, researchers analyzed health data for nearly two million adults with and without CAA, tracking new dementia diagnoses from 2016 to 2022. All participants were at least 65 years old and covered by Medicare.

The adults were grouped into four medical categories: no CAA or stroke, CAA only, stroke only, or both CAA and stroke.

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About 42% of people with CAA were diagnosed with dementia within five years, compared to only 10% of those without it — roughly a fourfold difference. 

The risk remained elevated even if the person had no history of stroke.

“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,” study author Samuel S. Bruce, an assistant professor of neurology at Weill Cornell Medicine in New York City, said in a press release.

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“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,” he added.

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The early research will be presented as a preliminary study at the American Stroke Association’s International Stroke Conference this week in New Orleans, and it may undergo further peer review before final publication.

While the study found a strong link, it has limitations. For example, it does not fully explain how these protein deposits damage brain function in ways other than causing a stroke.

Additionally, researchers used administrative diagnosis codes from Medicare insurance claims, which Bruce said are “imperfect” alternatives for clinical diagnoses.

“These codes are an imperfect proxy for clinical diagnoses, and misclassifications can occur,” he said in the release.

To improve accuracy, researchers relied only on diagnosis codes that had been shown to be reliable in past studies. However, they did not have access to brain imaging, which could have provided more precise confirmation of CAA and stroke diagnoses.

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People may be screened for the condition if they are older and have new cognitive symptoms that may indicate small-vessel disease, or if they have had a brain bleed or stroke that suggests CAA, according to medical sources.