The relationship between non-valvular atrial fibrillation and dementia

Date of ISAC Approval: 
Lay Summary: 
Atrial fibrillation (AF) is the most common heart rhythm disorder in daily cardiology practice. It results in an irregular heartbeat and various complaints. The worldwide number of patients with this rhythm disorder is increasing rapidly as the population becomes older and older. The risk of suffering a stroke in people with AF is 5 times higher than in people without AF. Stroke is the blockage of blood flow to portions of the brain, often caused by a blood clot. Patients with AF are often using medicines that help to prevent clots (blood thinners). AF may be associated with trouble with memory and thinking (cognitive impairment or dementia). The possible relationship between stroke, blood thinners, dementia and AF is not well understood. This study will investigate the association between AF and newly diagnosed (new-onset) dementia.
Technical Summary: 
The risk of both dementia and atrial fibrillation (AF) increases with age, and several studies have found an increased risk of dementia in AF patients, although findings are inconsistent. Several mechanisms for this association have been proposed, including potential causative factors such as micro emboli, cerebral microbleeds, variable cerebral perfusion and stroke-related dementia. However it is unclear whether this association exists independently or is related to shared vascular risk factors for AF and dementia. Furthermore, the potential modifying role of anticoagulation in AF - which reduces the risk of stroke by two-thirds - in its relationship with dementia is also unknown. This study will investigate the association between incident non-valvular AF and new-onset dementia in a cohort with incident non-valvular AF and a matched cohort without AF. Adjusted hazard ratios of the association between non-valvular AF and dementia compared with non-AF will be estimated using Cox regression. Sensitivity analyses will be performed excluding patients with a history of stroke and antidepressant use.
Health Outcomes to be Measured: 

Carlos Martinez - Chief Investigator - Institute for Epidemiology, Statistics and Informatics GmbH (Pharma Epi)
Alexander (Ander) Cohen - Collaborator - Kings College London
Anja Katholing - Collaborator - Institute for Epidemiology, Statistics and Informatics GmbH (Pharma Epi)
Antonio Curcio - Collaborator - University Magna Graecia
Bob Weijs - Collaborator - Maastricht University
Carlos Martinez - Corresponding Applicant - Institute for Epidemiology, Statistics and Informatics GmbH (Pharma Epi)
Michela Giustozzi - Collaborator - University of Perugia
Saulius Sudikas - Collaborator - Vilnius City Clinical Hospital
Thalia Field - Collaborator - University Of British Columbia

HES Admitted;HES Outpatient;ONS;Patient IMD