Anticoagulants could stave off increased risk of dementia associated with AF
medwireNews: Study findings show an increased risk of dementia in older people with atrial fibrillation (AF) and support the use of anticoagulants to reduce the likelihood.
The risk of all-cause dementia was increased by 40% among patients who either had AF at the start of the study in 2001–2004 or who developed incident AF during 9 years of follow-up. And among those taking anticoagulant drugs there was a 60% reduction in risk. By contrast, there was no significant association between dementia and the use of antiplatelet drugs.
“Assuming that there was a causal relationship between use of anticoagulant drugs and a reduced risk of dementia, we estimated that approximately 54% of the dementia cases would have been hypothetically prevented if all patients with AF had received anticoagulant drugs”, say Mozhu Ding (Karolinska Institutet, Stockholm, Sweden) and co-researchers.
“Our findings shed light on the added cognitive benefit of anticoagulant drugs in patients with AF apart from stroke prevention. Additional efforts should be made to improve anticoagulant treatment in elderly patients with AF, since anticoagulation remains under prescribed, particularly in older patients with AF.”
AF was diagnosed in 243 of 2685 dementia-free participants of the Swedish National Study on Aging and Care in Kungsholmen at baseline and a further 279 developed incident AF during follow-up. These individuals were aged 60 years and older. Dementia developed in 399 individuals, of whom 6.2% had Alzheimer’s disease (AD), while 2.5% developed either vascular dementia or mixed dementia. Among the 128 patients taking anticoagulants, 11% developed dementia, compared with 22% of 342 not taking anticoagulant drugs.
AF as a time-varying variable was significantly associated with an accelerated average decline in Mini-Mental State Examination score and a significantly increased risk of dementia after taking into account demographic factors, lifestyle factors and chronic diseases.
But the researchers note in Neurology that in propensity score-weighted Cox regression models, the association between AD and dementia was only significant for women and carriers of the APOE ε4 allele, with increased risks of 46% and 74%, respectively.
Despite dementia risk being increased in carriers of the APOE ε4 allele, AF was not associated with a significantly increased risk of AD; a significant increase in risk, at 88%, was only seen for combined vascular and mixed dementia.
This finding “further highlights the role of cerebrovascular disease as the culprit of AF-related cognitive impairment”, say Luciano Sposato (Western University, London, Ontario, Canada) and Lin Chen (University of Minnesota, Minneapolis, USA) in a related editorial.
This is indirectly supported by the association between AF and dementia risk being limited to women, who “endure a higher risk of AF-related ischemic stroke than men,” they add. However, the editorialists also point out that “cerebrovascular pathology does not seem to be enough by itself”.
Indeed, the current study showed that AF was associated with a sixfold increase in the risk of combined vascular and mixed dementia among carriers of the APOE ε4 allele relative to noncarriers.
Ding and colleagues say that “this indicates that while AF itself might not be enough to cause clinical dementia, the coexistence of AD pathology associated with APOE ε4 allele and cerebrovascular lesions related to AF could lead to a substantial risk of dementia than either process alone.”
By Lucy Piper
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