High Blood Pressure May Affect Thinking

By Robert Shmerling, M.D.
Content provided by the Faculty of the Harvard Medical School

High blood pressure may be linked to a decline in thinking ability, a study suggests. The research used data from a long-term study of 20,000 people. All were over age 45. It found that for every 10-point increase in diastolic blood pressure, the odds of having problems with thinking increased 7%. Diastolic pressure is the bottom number in a blood pressure reading. It measures pressure while the heart relaxes between beats. The study appeared in the journal Neurology. HealthDay News wrote about it August 24.

What Is the Doctor's Reaction?

High blood pressure is often called "the silent killer." The reputation is well-deserved. It's "silent" because high blood pressure (also called hypertension) causes no symptoms. It's deadly because having untreated high blood pressure greatly increases your risk of heart attack and stroke.

Now, a new study suggests that high blood pressure can cause another important problem: memory loss.

The study included almost 20,000 adults who were at least 45 years old. Researchers measured their blood pressure and gave them tests of thinking ability. They adjusted the results to account for other factors (such as age) that could affect brain function. They found a strong link between high blood pressure and problems with memory or thinking.

The diastolic blood pressure reading seemed to be most important. That's the bottom number of a standard blood pressure reading. The chances of someone having problems with brain function were 7% higher for every 10-point increase in diastolic blood pressure.

This new research is among the most compelling to link high blood pressure with brain problems. But it does not answer some important questions:

  • Does the prevention of high blood pressure prevent problems with brain function, dementia or other brain diseases?

  • Does the treatment of high blood pressure prevent or even reverse brain function problems?

  • What is the ideal blood pressure that people should aim for to lessen the risk of brain disease?

  • How does high blood pressure lead to memory loss or other problems with brain function?

We don't yet have the answers to these questions. But we know that high blood pressure has other negative health effects. And that means it's important to do what you can to reduce your risk of developing this condition.

What Changes Can I Make Now?

You can make changes now to keep your blood pressure normal. This study suggests (but does not prove) that these steps also could lower your risk of problems with memory and thinking in the future.

Such changes include:

  • Losing excess weight

  • Exercising regularly

  • Restricting your salt intake

  • Drinking only a moderate amount of alcohol

  • Not smoking

If you're used to eating foods with a lot of salt, restricting salt intake may not sound appetizing. But once you get used to a low-salt diet, your old diet will taste much too salty! If you're not sure whether your diet is low in salt, meet with a nutritionist.

Learn about the Dietary Approaches to Stop Hypertension (DASH) eating plan. This diet is low in fat and red meat. It includes lots of fruits, vegetables, whole grains, fish, poultry and nuts. Along with salt restriction, this diet has been proven to help lower blood pressure. It may also help to prevent high blood pressure from developing in the first place.

Get your blood pressure checked regularly. If it's high and you are not able to lower it with diet and exercise, talk to your doctor about medicines that can help. This is especially important for those who have a high risk of developing high blood pressure. Factors that increase risk include smoking or a family history of high blood pressure.

If you have had high blood pressure readings in the past, consider buying a device to measure your blood pressure at home. These devices have become more accurate, easier to use and more affordable in recent years. Bring it with you to your next doctor's visit. Compare your readings with those measured by your doctor.

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High blood pressure, or hypertension, is known as the "silent killer" because: