Association between cognitive impairment and atrial fibrillation: a systematic review.

Purpose: Although it is well established that atrial fibrillation (AF) causes ischemic stroke, the relationship between AF and cognitive impairment is unclear. The aim of this systematic review is to investigate whether AF is associated with cognitive impairment or dementia.
Materials and Methods: An electronic search of Medline, Embase, Psychlit, Cinahl and the Cochrane library was performed in March 2000 to identify studies in which the primary aim was to investigate the relationship between AF and cognitive impairment or dementia. Studies with relevant data on both cognitive function and AF (even if that was not the primary aim of the study) were also identified. Further references were identified from these sources.
Results: Ten studies were identified, of which 4 were cross-sectional, 5 were case-control, and 1 was a prospective cohort study. The methodology and measures of cognition varied substantially, so it was not valid to apply formal meta-analysis techniques to the results. However, the methodology in all the studies was flawed in at least 1 aspect, including the reporting of results, external validity, and internal validity. Seven studies found an association between AF and at least 1 measure of cognition whereas 3 studies did not find an association.
Conclusion: The evidence that AF is associated with cognitive impairment is inconclusive. Further studies are required to establish whether there is a relationship between AF and cognitive impairment, and if so, whether the relationship is causal.