Odd Rhythm Linked to Earlier Memory Issues

Older adults with one type of abnormal heart rhythm may be more likely to develop problems with memory and thinking, a study suggests. The study used information on 5,152 people in a long-term health study. All were age 65 and older when the study began. Each year, they took a 100-point test of memory and thinking ability. Researchers kept track of people for an average of 7 years. In that time, 552 developed a heart rhythm problem called atrial fibrillation. This condition involves the heart's upper chambers, the atria. They beat fast and in a chaotic way instead of a regular pattern. Thinking and memory scores tended to fall faster for those with atrial fibrillation than for other people in the study. Test scores below 78 are linked with dementia. The average score for people with atrial fibrillation dropped below 78 at age 85. That was 2 years earlier than for people without this rhythm problem. The study does not prove that atrial fibrillation causes thinking problems. Researchers will try to find out why the link exists. The journal Neurology published the study. HealthDay News wrote about it June 5.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Do you know what a "cardiac dysrhythmia" is? In fact, it could mean many things.

A cardiac dysrhythmia is any abnormal heart rhythm. Another common term for this is "cardiac arrhythmia."

An abnormal heart rhythm may cause the heart to beat abnormally fast or slow. The beats may not follow a steady pattern. Or a combination of problems can occur. Abnormal heart rhythms are a common form of heart disease. They can be harmless or life-threatening. Atrial fibrillation is among the most common types of abnormal heart rhythm.

The normal heart beat is regular and well-organized. The top part of the heart (the atria) beats first and the bottom part (the ventricles) beats soon after. The pulse you can feel at your wrist is caused by the regular beating of the ventricles. The normal heart beats 60 to 90 times per minute.

Atrial fibrillation is quite different:

• The atria quiver in a chaotic way.
• The pulse is often fast (well over 100 beats per minute) and does not follow a regular pattern.
• Many people have no symptoms. However, some are bothered by palpitations or feeling faint.
• The real danger is that a blood clot may form in the quivering atria. This clot can travel to other parts of the body. If it travels to the brain, it can cause a stroke.

The increased risk of stroke linked to atrial fibrillation is well known. And it's the reason blood thinners are routinely prescribed for people with this condition. But a new study cites a new risk: poor memory and thinking.

The medical journal Neurology published the study online. Researchers studied more than 5,000 people over age 64. Here's what they found:

• About 11% developed atrial fibrillation.
• Measures of memory and thinking got worse with age.
• These measures of brain function got worse much faster among those with atrial fibrillation.
• Dementia could develop about 2 years earlier among those with atrial fibrillation compared with those who did not have this heart rhythm.

This study does not prove that atrial fibrillation actually causes dementia. There may be other explanations for the link.

For example, perhaps atrial fibrillation caused strokes that led to memory problems. People with signs of a stroke were excluded from the study. However, small strokes may not cause obvious symptoms and so could have been missed. Another possibility is that other diseases (such as high blood pressure or diabetes) that make atrial fibrillation more likely also contribute to brain disease. The study did try to account for this possibility, though.

This study is important because it raises questions about the relationship between atrial fibrillation and brain function. The answers could lead to treatments that help people avoid problems with memory and thinking.

What Changes Can I Make Now?

The health risks linked to atrial fibrillation -- including a possible link to dementia -- are good reasons to do what you can to avoid it.

You can reduce your chances of developing atrial fibrillation. These steps may help:

• Lose excess weight.
• Exercise regularly.
• Don't smoke.
• Avoid drinking large amounts of alcohol.
• Improve your cholesterol levels (including HDL, LDL and total cholesterol).
• Get your blood pressure checked. If it's high, work with your doctor to lower it.
• If you take thyroid medicine, get regular tests of thyroid function.

Unfortunately, even if you do all of these things, you could still develop atrial fibrillation. Many cases develop among people with only average risk of the condition.

If you have atrial fibrillation, talk to your doctor about ways you can keep your heart healthy -- and regular.

What Can I Expect Looking to the Future?

In the future, you can expect to hear about more research that confirms (or refutes) the link between atrial fibrillation and dementia. If the link is confirmed, future studies should determine:

• Why atrial fibrillation increases the risk of memory and thinking problems
• Whether people with atrial fibrillation can take steps to prevent dementia
• How atrial fibrillation can be prevented in the first place
• How to make the treatment of atrial fibrillation easier and safer

These answers will come none too soon. People are more likely to develop atrial fibrillation as they get older. So the number of people with this condition is expected to increase dramatically in the near future.