Cognitive impairment associated with atrial fibrillation: a meta-analysis.

BACKGROUND: Atrial fibrillation (AF) has been linked with an increased risk for cognitive impairment and dementia.

PURPOSE: To complete a meta-analysis of studies examining the association between AF and cognitive impairment.

DATA SOURCES: Search of MEDLINE, PsycINFO, Cochrane Library, CINAHL, and EMBASE databases and hand search of article references.

STUDY SELECTION: Prospective and nonprospective studies reporting adjusted risk estimates for the association between AF and cognitive impairment.

DATA EXTRACTION: Two abstracters independently extracted data on study characteristics, risk estimates, methods of AF and outcome ascertainment, and methodological quality.

DATA SYNTHESIS: Twenty-one studies were included in the meta-analysis. Atrial fibrillation was significantly associated with a higher risk for cognitive impairment in patients with first-ever or recurrent stroke (relative risk [RR], 2.70 [95% CI, 1.82 to 4.00]) and in a broader population including patients with or without a history of stroke (RR, 1.40 [CI, 1.19 to 1.64]). The association in the latter group remained significant independent proof of clinical stroke history (RR, 1.34 [CI, 1.13 to 1.58]). However, there was significant heterogeneity among studies of the broader population (I2 = 69.4%). Limiting the analysis to prospective studies yielded similar results (RR, 1.36 [CI, 1.12 to 1.65]). Restricting the analysis to studies of dementia eliminated the significant heterogeneity (P = 0.137) but did not alter the pooled estimate substantially (RR, 1.38 [CI, 1.22 to 1.56]).

LIMITATIONS: There is an inherent bias because of confounding variables in observational studies. There was significant heterogeneity among included studies.

CONCLUSION: Evidence suggests that AF is associated with a higher risk for cognitive impairment and dementia, with or without a history of clinical stroke. Further studies are required to elucidate the association between AF and subtypes of dementia as well as the cause of cognitive impairment.