Blood Pressure Spikes May Cloud Elders' Minds

Dec. 15, 2008 - An elderly person's ability to think clearly gets worse as his or her blood pressure gets high, a small study suggests.

The link between high blood pressure and mental function comes from a study of 36 women and men 60 to 87 by Jason C. Allaire, PhD, and colleagues at North Carolina State University in Raleigh.

While the study suggests a link, it's not clear what causes what. Previous studies have found that elderly people with high blood pressure have poorer mental skills than those with normal blood pressure. But the stress of struggling with a mental task can raise blood pressure and may contribute to the link.

In their study, Allaire and colleagues had their elderly participants measure their blood pressure and complete mental-function tests every morning and every evening for 60 days in a row.

After controlling for improvements due to practice, the researchers found that as an individual's blood pressure went up, his or her test performance went down.

The type of task that linked to blood pressure was inductive reasoning. That's the kind of reasoning that allows you to make generalizations based on specific instances. The test used in the study asked participants to identify a pattern in a series of letters and to predict the next letter in the series.

The effect of blood pressure only appeared when a person's systolic blood pressure (the first or top number) was 130 or higher. A reading of 120 to 139 is considered borderline high blood pressure. Hypertension -- true high blood pressure -- isn't diagnosed until systolic blood pressure reaches 140 (or when diastolic blood pressure reaches 90).

The findings, Allaire suggests, indicate that some elderly people may have trouble thinking clearly in stressful situations that cause their blood pressure to spike.

The study appears in the current issue of the Journal of Gerontology: Psychological Sciences.