NEW YORK (Reuters Health), Sep 26 - Even in the absence of clinical stroke, atrial fibrillation (AF) is associated with impaired cognitive function and reduced hippocampal volume, according to findings from the German Atrial Fibrillation Competence Network (AFNET) study.
"AF leads to a hypercoagulatory state that could give rise to subclinical cerebral embolism," Dr. Stefan Knecht and colleagues note in the European Heart Journal for September. "Whether AF also increases the risk of cognitive decline and dementia independently of stroke is unclear."
The research team at the University of Munster examined this question in a cohort of 87 patients with AF "considerably younger than those in previous studies," and a comparator group of 446 individuals without AF matched by birth date (ages 37-84 years).
Individuals with depression, dementia, or a history of stroke were excluded and high-field MRI of the brain was used to rule out covert brain infarction.
Participants underwent in-depth neurocognitive evaluation. After controlling for age, gender, education, and other risk factors, AF was significantly and independently associated with worse performance in tasks of learning, memory, attention, and executive functions (p < 0.01 for each).
AF was also significantly and independently associated with hippocampal atrophy, but not with total brain volume or white matter hyperintensities.
According to the investigators, "a comparable load of white-matter lesions in individuals with and without AF suggests that AF does not damage the brain by small vessel pathology but by other mechanisms -- possibly microembolism," or by abnormal hemostasis, endothelial damage, platelet dysfunction, or low cardiac output.
"Whether novel antithrombotic or rhythm-control treatments of AF can prevent cognitive decline should be studied in controlled trials," the team concludes.
Eur Heart J 2008;29:2125-2132.
Last Updated: 2008-09-26 8:30:28 -0400 (Reuters Health)
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