Heart failure and Alzheimer's disease

Atrial Fibrillation and Risk of Dementia/Cognitive Decline

Emerging evidence suggests a link between atrial fibrillation and subsequent development of dementia. While a majority of risk can be attributed to cardioembolic stroke secondary to atrial fibrillation, additional risk is apparent, and may be driven by vascular inflammation and changes in cerebral perfusion. Medical therapies including anticoagulation, statin therapy, and angiotensin-renin-aldosterone axis antagonists may reduce dementia risk. Procedural therapies such as atrial fibrillation catheter ablation and left atrial appendage closure may also prove to be important mediators of acute and long-term risk. In this paper, we review the data supporting a link between atrial fibrillation and dementia syndromes, pathophysiologic mechanisms and the potential roles of medical and procedural therapies at reducing such risk.

Cardiac Output and Cerebral Blood Flow

Cerebral blood flow (CBF) is rigorously regulated by various powerful mechanisms to safeguard the match between cerebral metabolic demand and supply. The question of how a change in cardiac output (CO) affects CBF is fundamental, because CBF is dependent on constantly receiving a significant proportion of CO. The authors reviewed the studies that investigated the association between CO and CBF in healthy volunteers and patients with chronic heart failure. The overall evidence shows that an alteration in CO, either acutely or chronically, leads to a change in CBF that is independent of other CBF-regulating parameters including blood pressure and carbon dioxide. However, studies on the association between CO and CBF in patients with varying neurologic, medical, and surgical conditions were confounded by methodologic limitations. Given that CBF regulation is multifactorial but the various processes must exert their effects on the cerebral circulation simultaneously, the authors propose a conceptual framework that integrates the various CBF-regulating processes at the level of cerebral arteries/arterioles while still maintaining autoregulation. The clinical implications pertinent to the effect of CO on CBF are discussed. Outcome research relating to the management of CO and CBF in high-risk patients or during high-risk surgeries is needed.

Heart failure and dementia: survival in relation to types of heart failure and different dementia disorders

Aims

Heart failure (HF) and dementia frequently coexist, but little is known about their types, relationships to each other and prognosis. The aims were to (i) describe patients with HF and dementia, assess (ii) the proportion of specific dementia disorders in types of HF based on ejection fraction and (iii) the prognostic role of types of HF and dementia disorders.

Methods and results

The Swedish Heart Failure Registry (RiksSvikt) and The Swedish Dementia Registry (SveDem) were record-linked. Associations between dementia disorders and HF types were assessed with multinomial logistic regression and survival was investigated with Kaplan–Meier analysis and multivariable Cox regression. We studied 775 patients found in both registries (55% men, mean age 82 years). Ejection fraction was preserved in 38% of patients, reduced in 34%, and missing in 28%. The proportions of dementia disorders were similar across HF types. Vascular dementia was the most common dementia disorder (36%), followed by other dementias (28%), mixed dementia (20%), and Alzheimer disease (16%). Over a mean follow-up of 1.5 years, 76% of patients survived 1 year. We observed no significant differences in survival with regard to HF type (P = 0.2) or dementia disorder (P = 0.5). After adjustment for baseline covariates, neither HF types nor dementia disorders were independently associated with survival.

Conclusions

Heart failure with preserved ejection fraction was the most common HF type and vascular dementia was the most common dementia disorder. The proportions of dementia disorders were similar across HF types. Neither HF types nor specific dementia disorders were associated with survival.

Comorbidity profile in dementia with Lewy bodies versus Alzheimer's disease: a linkage study between the Swedish Dementia Registry and the Swedish National Patient Registry

Introduction

Compared to Alzheimer’s disease (AD), dementia with Lewy bodies (DLB) is usually associated with a more complex clinical picture and higher burden of care. Yet, few investigations have been performed on comorbidities and risk factors of DLB. Therefore, we aimed to compare clinical risk factors and comorbidity profile in DLB and AD patients using two nationwide registries.

Methods

This is a linkage study between the Swedish dementia registry (SveDem) and the Swedish National Patient Registry conducted on 634 subjects with DLB and 9161 individuals with AD registered during the years 2007–2012. Comorbidity profile has been coded according to the International Classification of Diseases version 10 (ICD 10) in addition to the date of each event. The main chapters of the ICD-10, the Charlson score of comorbidities and a selected number of neuropsychiatric diseases were compared between the DLB and AD groups. Comorbidity was registered before and after the dementia diagnosis.

Results

“Mental and behavioral disorders”, “diseases of the nervous system”, “diseases of the eye and adnexa”, diseases of the “circulatory”, “respiratory”, and “genitourinary” systems, “diseases of the skin and subcutaneous tissue” and “diseases of the musculoskeletal system and connective tissue” occurred more frequently in the DLB group after multivariate adjustment. Depression [adjusted OR = 2.12 (95%CI 1.49 to 3.03)] and migraine [adjusted OR = 3.65 (95%CI 1.48 to 9.0)] were more commonly recorded before the diagnosis of dementia in the DLB group. Following dementia diagnosis, ischemic stroke [adjusted OR = 1.89 (95%CI 1.21 to 2.96)] was more likely to happen among the DLB patients compared to the AD population.

Conclusions

Our study indicated a worse comorbidity profile in DLB patients with higher occurrence of depression, stroke and migraine compared with the AD group. Deeper knowledge about the underlying mechanisms of these associations is needed to explore possible reasons for the different pattern of comorbidity profile in DLB compared to AD and their prognostic significance.