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OBJECTIVE	Atrial fibrillation is associated with decline of cognitive function .
OBJECTIVE	Observational evidence suggests that anticoagulation might protect against this decline .
OBJECTIVE	We report the first randomized controlled trial evidence on the effect of anticoagulation on cognitive function in elderly patients with atrial fibrillation .
METHODS	A total of 973 patients aged75 years with atrial fibrillation were recruited from primary care and randomly assigned to warfarin ( n = 488 ; target international normalized ratio , 2-3 ) or aspirin ( n = 485 ; 75 mg/d ) .
METHODS	Neither participants nor investigators were masked to group assignment .
METHODS	Follow-up was for a mean of 2.7 years ( SD , 1.2 ) .
METHODS	Cognitive outcome was assessed using the Mini-Mental State Examination at 9 - , 21 - , and 33-month follow-up .
METHODS	Participants who had a stroke were censored from the analysis , which was by intention to treat with imputation for missing data .
RESULTS	There was no difference between mean Mini-Mental State Examination scores in people assigned to warfarin or aspirin at 9 or 21 months .
RESULTS	At 33-month follow-up , there was a nonsignificant difference of 0.56 in favor of warfarin that decreased to 0.49 ( 95 % confidence interval , -0.01 to 0.98 ) after imputation .
CONCLUSIONS	We found no evidence that anticoagulation confers clinically important protection over aspirin against cognitive decline as measured by the Mini-Mental State Examination in atrial fibrillation in the first 33 months of treatment other than that provided by preventing clinical stroke .
BACKGROUND	http://www.controlled-trials.com .
BACKGROUND	Unique identifier : ISRCTN89345269 .

