Paroxysmal atrial fibrillation and related thromboembolism may be a hidden factor in the development of dementia

Abstract

We read the article entitled ‘Correlations between homocysteine and grey matter volume in patients with Alzheimer's disease’ by Park et al. with great interest.1 In this well‐designed research, they used brain magnetic resonance imaging to demonstrate that increased serum homocysteine levels were not associated with a decreased volume of cerebral grey matter in patients with Alzheimer's disease. Park et al. excluded patients with cardiovascular disease and recruited only patients with Alzheimer's disease, not vascular dementia. However, among elderly individuals, it is too difficult to determine which patients have vascular disease according to their medical history. Although patients may not have experienced any vascular events or symptoms, age‐ related arteriosclerosis is often present in this age group. Furthermore, because of silent attacks, these patients often have undiagnosed episodes of paroxysmal atrial fibrillation (AF). The prevalence of AF was found to be 9% in individuals >80 years of age and 0.1% in subjects <55 years of age.2 These data were derived from trials in which diagnosis was based on a 12‐lead electrocardiogram obtained during an office visit. AF is classified into three types based on episode duration: paroxysmal AF, persistent AF, and permanent AF.3 Although other types of AF can be easily diagnosed with a routine 12‐lead electrocardiogram, paroxysmal AF may be overlooked. To determine whether paroxysmal AF attacks have occurred, ambulatory monitoring is required. Therefore, it is presumed that the real‐world prevalence of AF is higher than that determined in trials.3