Skip to main content

Irregular Heartbeat Raises Risk of Dementia

The most common kind of chronically irregular heartbeat, known as atrial fibrillation, is associated with a greater risk of dementia, including Alzheimer's disease. This discovery by scientists at Group Health Research Institute and their collaborators was published online in advance of print on August 1 in the Journal of the American Geriatrics Society.
"Both atrial fibrillation and dementia increase with age," said Sascha Dublin, MD, PhD, a Group Health Research Institute assistant investigator who led the research. "Before our prospective cohort study, we knew that atrial fibrillation can cause stroke, which can lead to dementia. Now we've learned that atrial fibrillation may increase dementia risk in other, more subtle ways as well."

The results of Dr. Dublin's study suggest a relationship between atrial fibrillation and dementia beyond the connection through stroke. The people in the study had a mean age of 74 years when the study began. None had dementia or a history of stroke. At the beginning of the study, 4.3 percent had atrial fibrillation, and an additional 12.2 percent developed it during the study. In the course of the study, 18.8 percent developed some type of dementia. People with atrial fibrillation were more likely to have other cardiovascular risk factors and disease than were those without the condition. So the researchers looked to see if atrial fibrillation increased dementia risk more than just through its association with other kinds of heart disease.

Participants were followed for an average of seven years. Over this time, those with atrial fibrillation had a 40 percent to 50 percent higher risk of developing dementia of any type, including probable Alzheimer's disease, compared to those without atrial fibrillation. This was true even for people who did not also have a stroke during the follow-up period.

The research was part of Adult Changes in Thought (ACT), an ongoing joint project of the Group Health and University of Washington studying risk factors for dementia in older adults. Started in 1994 ACT is led by Dr. Dublin's co-author Group Health Vice President for Research and Group Health Research Institute Executive Director Eric B. Larson, MD, MPH. ACT focuses on finding ways to delay or prevent dementia, including Alzheimer's disease, and declines in memory and thinking. It aims to deepen understanding of how the body -- especially the brain -- ages. ACT participants are members of Group Health Cooperative, a nonprofit health care system in the U.S. Pacific Northwest.

Dr. Dublin's study, which ran from 1994 to 2008, followed 3,045 people. The researchers relied on Group Health's advanced electronic data systems to determine whether participants had atrial fibrillation. The cognitive function of all study participants was evaluated every two years with tests and interviews as part of ACT. Patients whose ACT tests indicated possible dementia had additional tests including physical, neurological, and psychological exams, and many also had brain scans. A panel of experts determined the correct diagnosis for patients with cognitive problems.

Atrial fibrillation affects 3 million Americans. Dr. Dublin says that some ways it might increase dementia risk are:

weakening the heart's pumping ability, leading to less oxygen going to the brain;
increasing the chance of tiny blood clots going to the brain, causing small, clinically undetected strokes;
a combination of these plus other factors that contribute to dementia such as inflammation.

Dr. Dublin said an important next step is studying whether any treatments for atrial fibrillation reduce the risk of developing dementia. The researchers also hope their results reach primary care providers, who are often the main doctors caring for people with atrial fibrillation, dementia, or both.

"Right now, we think we are protecting our patients' brains as long as they don't have a stroke, but tiny insults over time can add up," said Dr. Dublin, who is a primary care physician at Group Health. "This paper is a wakeup call, telling us that we need to learn more about how to protect brain function, while continuing to give patients with atrial fibrillation the best possible care."

The National Institute on Aging, part of the National Institutes of Health, funded this study.

Drs. Dublin and Larson's co-authors are Melissa L. Anderson, MS, Group Health Research Institute senior biostatistician; Sebastien J. Haneuse, PhD, who recently moved from Group Health Research Institute to Harvard School of Public Health; Group Health Research Institute Affiliate Investigators Susan R. Heckbert, MD, PhD, Paul K. Crane, MD, MPH, Linda Teri, PhD, and Susan M. McCurry, PhD, all of the University of Washington; Wayne McCormick, MD, MPH, of the University of Washington; James D. Bowen, MD, of the University of Washington and Swedish Neuroscience Institute; and John C. S. Breitner, MD, MPH, who recently moved from the University of Washington and Veterans Affairs Puget Sound Health Care System to McGill University, in Montreal, Quebec.

Sascha Dublin, Melissa L. Anderson, Sebastien J. Haneuse, Susan R. Heckbert, Paul K. Crane, John C. S. Breitner, Wayne McCormick, James D. Bowen, Linda Teri, Susan M. McCurry, Eric B. Larson. Atrial Fibrillation and Risk of Dementia: A Prospective Cohort Study. Journal of the American Geriatrics Society, 2011; DOI: 10.1111/j.1532-5415.2011.03508.x
Source: Group Health Research Institute, via EurekAlert.

Comments

Popular posts from this blog

Charging Implanted Heart Pumps Wirelessly

Mechanical pumps to give failing hearts a boost were originally developed as temporary measures for patients awaiting a heart transplant. But as the technology has improved, these ventricular assist devices commonly operate in patients for years, including in former vice-president Dick Cheney, whose implant this month celebrates its one-year anniversary. Prolonged use, however, has its own problems. The power cord that protrudes through the patient's belly is cumbersome and prone to infection over time. Infections occur in close to 40 percent of patients, are the leading cause of rehospitalization, and can be fatal. Researchers at the University of Washington and the University of Pittsburgh Medical Center have tested a wireless power system for ventricular assist devices. They recently presented the work in Washington, D.C. at the American Society for Artificial Internal Organs annual meeting, where it received the Willem Kolff/Donald B. Olsen Award for most promising research in

Autism and Eye Contact: Genes very much are involved

We have now a lot of evidence on genetic components in many disorders including neurological in both adults and kids. Autism is one such problem that has many genes involved. Research is still in full swing to find more genes and related pathways. However, one can find autistic features more phenotypically before genotyping. Eye contact is one of them. Studies have shown that autistic kids make less eye contact. This has been shown to have genetic component now. New research has uncovered compelling evidence that genetics plays a major role in how children look at the world and whether they have a preference for gazing at people's eyes and faces or at objects. The discovery by researchers at Washington University School of Medicine in St. Louis and Emory University School of Medicine in Atlanta adds new detail to understanding the causes of autism spectrum disorder. The results show that the moment-to-moment movements of children's eyes as they seek visual information about the

How much people depend on weather reports

Meteorologists on television, radio, online, and in newspapers supply weather reports to the average person over 100 times a month. Surveys demonstrated that the 300 billion forecasts accessed generate a value of $285 per household every year, or $32 billion for the entire United States. Odds are you have already watched one weather forecast today and will probably check out a few more. Accurate, timely forecasts are vital to everyday life, but just how critical may surprise you. Whether at work or play, you probably watch the weather quite closely. Most of us are at the weather person's mercy to know what to wear, what to expect, to prepare for the worst. New research shows the average United States household checks out a weather report more than three times a day. "It impacts pretty much every part of every activity we are involved with for the most part," Jeff Lazo, the director of the Societal Impacts Program at the National Center for Atmospheric Research (NCAR) in B