By Marilynn Larkin
NEW YORK (Reuters Health) - 27/6/2019
Atrial fibrillation (AF) is associated with an increased risk of dementia, even in individuals who have not had a stroke, a Korean database study reveals.
"Since AF is so common, it is worth increasing awareness and proactively detecting and treating these patients," Dr. Gregory Lip of the University of Liverpool, UK told Reuters Health by email. "As well as a higher risk of stroke, heart failure and death, the development of AF can be associated with an increased risk of dementia, in an elderly population."
"Oral anticoagulant use is central to AF management for stroke prevention, and our study also shows that it is associated with a decreased incidence of dementia," he added.
Dr. Lip and colleagues studied 262,611 individuals age 60 and older in the Korea National Health Insurance Service-Senior cohort who were stroke- and dementia-free at baseline (2002). Data included sociodemographic and socioeconomic information, insurance status, health check-up examinations, and medical and dental history. Participants were followed through 2013.
As reported online June 18 in the European Heart Journal, AF occurred in 10,435 participants over an observational period of 1,629,903 person years (0.64%/year). Affected subjects were older (mean, 71.7 vs. 70.7), had higher diastolic blood pressure, and more frequent heart failure and COPD than participants without AF.
Further, hypertension was significantly higher in the AF group, and the observation period was longer (median 86 months compared with 85 months in the AF-free group). Baseline cognitive function was not significantly different between the groups, and after propensity-score matching, baseline characteristics of both groups were similar.
During the study, 24% of participants in the AF group developed dementia (incidence, 4.1 per 100 person-years) compared to 14.4% of those without AF (2.7 per 100 person-years). After adjustment, the risk of dementia was significantly increased by AF, with a hazard ratio of 1.52, even after censoring for stroke (1.27). Overall, AF increased the risk of both Alzheimer's disease (HR 1.31) and vascular dementia (HR 2.11).
As Dr. Lip noted, oral anticoagulant use was associated with a preventive effect on dementia development among those with AF (HR 0.61). By contrast, an increasing CHA2DS2-VASc score (predicts risk of stroke in patients with nonrheumatic AF) was associated with a higher risk of dementia.
Dr. Lip said, "We need a holistic or integrated approach to AF management. (This) is not complicated and can be as simple as ABC: 'A' Avoid stroke with Anticoagulation; 'B' Better symptom management with rate or rhythm control; and 'C' Cardiovascular risk factor optimization, including lifestyle factors e.g. obesity reduction, avoiding excess alcohol, etc."
"Cardiologists need to counsel and educate (all) patients on the risks of AF, more than simply the cardiac ones," he added.
Dr. Greg A. Sachs, a Regenstrief Institute research scientist and Chief, Division of General Internal Medicine and Geriatrics at Indiana University School of Medicine in Indianapolis, commented by email that while the findings seem feasible, there are several limitations.
"In addition to being an observational study, and all of the limitations that come with drawing conclusions from any study using this methodology, there are other...concerns that are specific to the study," he told Reuters Health. "These include the use of a single screening tool to say that the subjects were dementia-free at study outset (could patients have had mild cognitive impairment not detected on screener; no information on function), as well as relying on medical records for diagnosis of dementia (tends to be under-documented), and that some types of dementia diagnoses appear not to have been captured (dementia with Lewy Bodies, frontotemporal dementia, etc.)."
"That said, this adds to a growing body of evidence that conditions previously...thought of as increasing the risk of stroke also appear to increase the risk of non-stroke dementias such as Alzheimer's disease," he noted. "Treating cardiovascular risk factors (blood pressure, glucose, lipids, and now AF) - even in mid-life - may be promising avenues for decreasing the risk of dementia as well as stroke."
"Given the observational nature of the study, I'd be careful not to push this too far," he added, "but it would be one more reason...in favor of using oral anticoagulant therapy in patients who develop AF. Decreasing risk of stroke is already a pretty persuasive reason, but some patients who might be on the fence about the treatment might find the potential for decreasing risk of Alzheimer's disease as a clincher."
Eur Heart J 2019.