Linking Atrial Fibrillation with Alzheimer's Disease: Epidemiological, Pathological, and Mechanistic Evidence

Higher ventricular rate during atrial fibrillation relates to increased cerebral hypoperfusions and hypertensive events

Atrial fibrillation (AF) is associated with cognitive impairment/dementia, independently of clinical cerebrovascular events (stroke/TIA). One of the plausible mechanisms is the occurrence of AF-induced transient critical hemodynamic events; however, it is presently unknown, if ventricular response rate during AF may impact on cerebral hemodynamics. AF was simulated at different ventricular rates (50, 70, 90, 110, 130 bpm) by two coupled lumped parameter validated models (systemic and cerebral circulation), and compared to corresponding control normal sinus rhythm simulations (NSR). Hemodynamic outcomes and occurrence of critical events (hypoperfusions and hypertensive events) were assessed along the internal carotid artery-middle cerebral artery pathway up to the capillary-venous bed. At the distal cerebral circle level (downstream middle cerebral artery), increasing ventricular rates lead to a reduced heart rate-related dampening of hemodynamic signals compared to NSR (p = 0.003 and 0.002 for flow rate and pressure, respectively). This response causes a significant progressive increase in critical events in the distal cerebral circle (p < 0.001) as ventricular rate increases during AF. On the other side, at the lowest ventricular response rates (HR 50 bpm), at the systemic-proximal cerebral circle level (up to middle cerebral artery) hypoperfusions (p < 0.001) occur more commonly, compared to faster AF simulations. This computational study suggests that higher ventricular rates relate to a progressive increase in critical cerebral hemodynamic events (hypoperfusions and hypertensive events) at the distal cerebral circle. Thus, a rate control strategy aiming to around 60 bpm could be beneficial in terms on cognitive outcomes in patients with permanent AF.

Effect of small-vessel disease on cognitive trajectory after atrial fibrillation-related ischaemic stroke or TIA

Post-stroke dementia is common but has heterogenous mechanisms that are not fully understood, particularly in patients with atrial fibrillation (AF)-related ischaemic stroke or TIA. We investigated the relationship between MRI small-vessel disease markers (including a composite cerebral amyloid angiopathy, CAA, score) and cognitive trajectory over 12 months. We included patients from the CROMIS-2 AF study without pre-existing cognitive impairment and with Montreal Cognitive Assessment (MoCA) data. Cognitive impairment was defined as MoCA < 26. We defined “reverters” as patients with an “acute” MoCA (immediately after the index event) score < 26, who then improved by ≥ 2 points at 12 months. In our cohort (n = 114), 12-month MoCA improved overall relative to acute performance (mean difference 1.69 points, 95% CI 1.03–2.36, p < 0.00001). 12-month cognitive impairment was associated with increasing CAA score (per-point increase, adjusted OR 4.09, 95% CI 1.36–12.33, p = 0.012). Of those with abnormal acute MoCA score (n = 66), 59.1% (n = 39) were “reverters”. Non-reversion was associated with centrum semi-ovale perivascular spaces (per-grade increase, unadjusted OR 1.83, 95% CI 1.06–3.15, p = 0.03), cerebral microbleeds (unadjusted OR 10.86, 95% CI 1.22–96.34, p = 0.03), and (negatively) with multiple ischaemic lesions at baseline (unadjusted OR 0.11, 95% CI 0.02–0.90, p = 0.04), as well as composite small-vessel disease (per-point increase, unadjusted OR 2.91, 95% CI 1.23–6.88, p = 0.015) and CAA (per-point increase, unadjusted OR 6.71, 95% CI 2.10–21.50, p = 0.001) scores. In AF-related acute ischaemic stroke or TIA, cerebral small-vessel disease is associated both with cognitive performance at 12 months and failure to improve over this period.

Getting to the Heart of Alzheimer Disease

In a somewhat narrow diagnostic lens, Alzheimer disease (AD) has been considered a brain-specific disease characterized by the presence of Aβ (β-amyloid) plaques and tau neural fibrillary tangles and neural inflammation; these pathologies lead to neuronal death and consequently clinical symptoms, such as memory loss, confusion, and impaired cognitive function. However, for decades, researchers have noticed a link between various cardiovascular abnormalities and AD-such as heart failure, coronary artery disease, atrial fibrillation, and vasculopathy. A considerable volume of work has pointed at this head to heart connection, focusing mainly on associations between cerebral hypoperfusion and neuronal degradation. However, new evidence of a possible systemic or metastatic profile to AD calls for further analysis of this connection. Aβ aggregations-biochemically and structurally akin to those found in the typical AD pathology-are now known to be present in the hearts of individuals with idiopathic dilated cardiomyopathy, as well as the hearts of patients with AD. These findings suggest a potential systemic profile of proteinopathies and a new hypothesis for the link between peripheral and central symptoms of heart failure and AD. Herein, we provide an overview of the cardiovascular links to Alzheimer disease.

Protective effects of oral anticoagulants on cerebrovascular diseases and cognitive impairment in patients with atrial fibrillation: protocol for a multicentre, prospective, observational, longitudinal cohort study (Strawberry study)

INTRODUCTION

Non-valvular atrial fibrillation (NVAF) is known as a robust risk factor for stroke. Recent reports have suggested a risk of dementia with NVAF, but much remains unknown regarding the relationship between this mechanism and the potential protective effects of novel anticoagulants (direct oral anticoagulants (DOACs), or non-vitamin K oral anticoagulants).

METHODS AND ANALYSIS

This study, the strategy to obtain warfarin or DOAC's benefit by evaluating registry, is an investigator-initiated, multicentre, prospective, observational, longitudinal cohort study comparing the effects of warfarin therapy and DOACs on cerebrovascular diseases and cognitive impairment over an estimated duration of 36 months. Once a year for 3 years, the activities of daily living and cognitive functioning of non-demented patients with NVAF will be assessed. Demographics, risk factors, laboratory investigations, lifestyle, social background and brain MRI will be assessed.

ETHICS AND DISSEMINATION

This protocol has been approved by the ethics committee of the National Center for Geriatrics and Gerontology (No. 1017) and complies with the Declaration of Helsinki. Informed consent will be obtained before study enrolment and only coded data will be stored in a secured database. The results will be published in peer-reviewed journals and presented at scientific meetings to ensure the applicability of the findings in clinical practice.

TRIAL REGISTRATION NUMBER

UMIN000025721.

Atrial Fibrillation, Cognitive Decline, and Dementia: an Epidemiologic Review

PURPOSE OF REVIEW

Atrial fibrillation (AF) and dementia are both prevalent diseases in aging societies, which exert a great economic burden worldwide. Although a handful of epidemiologic studies have indicated that AF is independently associated with faster cognitive decline and a higher risk of dementia, there is still a lack of comprehensive understanding of the observed association. In this review, we summarize evidence from major epidemiologic studies concerning AF-related cognitive decline and dementia, the potential mechanisms underlying their association, and the cognitive benefits of treatment options.

RECENT FINDINGS

A large majority of population-based longitudinal studies have consistently shown an independent association of AF with cognitive decline and dementia with varying effect sizes, depending on the age of the study population and the presence of clinical stroke. The underlying pathways linking AF to cognitive phenotypes may involve systemic inflammation, cerebral hypoperfusion, and cerebral small vessel disease and microemboli. However, current evidence is insufficient to support the potential benefits of AF treatment in reducing risk of cognitive decline and dementia.

SUMMARY

Current epidemiologic research suggests that AF contributes to cognitive decline and dementia, independent of a history of stroke. Further work is warranted to elucidate the potential mechanisms underlying this association, and more well-designed studies are needed to explore the possible cognitive benefits of different therapeutic options in patients with AF.