Dementia and mild cognitive impairment were less common among patients prescribed direct oral anticoagulants (DOACs) for newly diagnosed atrial fibrillation (AF) compared with those prescribed vitamin K antagonists (VKAs), in a UK cohort study.

The authors used electronic health records from the UK Clinical Practice Research Datalink, linked to Hospital Episodes Statistics and Index of Multiple Deprivation data, to identify first-time oral anticoagulant users with non-valvular AF diagnosed between 2012 and 2018.

They compared the incidence of dementia and mild cognitive impairment in patients prescribed VKAs and those prescribed DOACs.

The statistical analysis accounted for variables such as calendar time and time on treatment, sociodemographic and lifestyle factors, clinical comorbidities and other medication.

Of 39,200 first-time oral anticoagulant users (44.6% female), median age 76 years, 20,687 (53%) were prescribed a VKA and 18,513 (47%) a DOAC at baseline.

Demographic and lifestyle factors were similar in those prescribed DOACs and VKAs and there was no difference in the history of stroke, a major risk factor for dementia, between the different treatment groups.

A total of 1,258 patients (3.2%) had a diagnosis of dementia recorded by their GP with an incidence of 16.5 per 1,000 person-years. Overall, 1,488 patients (4.0%) received a diagnosis of mild cognitive impairment, with an incidence rate of 20.05 per 1,000 person-years.

In the whole cohort, compared with VKA therapy DOAC treatment for AF was associated with:

• 16% reduction in dementia diagnosis; adjusted hazard ratio (HR) 0.84 (95% CI: 0.73-0.98)

• 26% reduction in mild cognitive impairment; adjusted HR 0.74 (95% CI: 0.65-0.84)

Dementia risk is almost double in patients with AF. This could be due to silent cerebral infarcts, microemboli or systemic inflammation. Certainly, cerebral hypoperfusion is linked to neurodegeneration.

Oral anticoagulant treatment is recommended to reduce the risk of stroke in high-risk individuals with AF and could potentially protect patients from the excess dementia risk associated with this arrhythmia.

The authors conclude:

‘We observed that individuals taking DOACs for AF were less likely to be diagnosed with dementia and mild cognitive impairment than those taking VKAs, after adjusting for potential confounding factors.

‘While further evidence, including from randomised controlled trials, would strengthen this finding, it may be relevant to consider cognitive risk profile when prescribing oral anticoagulants for AF among older individuals.’

Dr Peter Savill