Study: AF stroke survivors may have greater chance of developing dementia

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Stroke survivors who have atrial fibrillation (AF) may be at higher risk of developing dementia than stroke survivors who do not have the heart condition, according to a meta-analysis published in the March 8 edition of Neurology.

A particular focus of interest has also been on the incidence of dementia after stroke or transient ischemic attack in people with or without AF at the time of stroke diagnosis, according to the study authors, but they noted that the current “evidence is conflicting.”

The research analyzed 15 studies—one of which had to be excluded because the Mini-Mental State Examination scores between patients with or without AF could not be pooled—where people with AF were compared with those without atrial fibrillation and followed to determine who developed dementia over time.

The meta-analysis assessed 46,637 participants with an average age of 71.7 years. Pooled odds ratios for AF and dementia were calculated using the random effects model, with heterogeneity assessed using I 2.
 
C.S. Kwok, MSc, from the Stroke Research Group at the Norfolk and Norwich University Hospital in Norfolk, England, and colleagues found that stroke survivors with AF were 2.4 times more likely to develop dementia than stroke survivors who did not have the heart condition. About 25 percent of patients with stroke and AF were found to have developed dementia during follow-up.

When stratified by participants, the association was significant (with little heterogeneity) in studies focusing solely on patients with stroke (seven studies, I 2, 10 percent), and of borderline significance (with substantial heterogeneity) for studies in broader populations (seven studies, I 2, 87 percent). For conversion of mild cognitive impairment to dementia, one study showed a significant association with AF.

"These results may help us identify potential treatments that could help delay or even prevent the onset of dementia," said the study’s senior author Phyo Kyaw Myint, MD, of the University of East Anglia in Norfolk, England. "Options could include more rigorous management of cardiovascular risk factors or of atrial fibrillation, particularly in stroke patients."

Though the results show a clear association in stroke patients, Myint warned that signs of a link in the general population–as suggested by some earlier studies–were inconclusive.

The authors also said that one major limitation of the existing review was the inclusion of different study designs, e.g., retrospective studies where it was not possible to confirm the temporal relationship between AF and the subsequent onset of dementia.

"There remains considerable uncertainty about any link in the broader population," he said.

The researchers said further high quality research was now needed to establish whether the link between atrial fibrillation and dementia in stroke patients was causal.