New research indicates that high and abnormally low blood pressures can have a detrimental effect on one's thinking ability or cognitive function.

However, the association seems to be influenced by age, educational level, and use of blood pressure drugs.

The findings are based on a study of 847 subjects who completed tests of cognitive function up to seven times over 11 years, Dr. Shari R. Waldstein of the University of Maryland in Baltimore and colleagues report in the medical journal Hypertension.

High systolic blood pressures, the "upper" number on a standard reading, were linked to cognitive decline in older subjects.

By contrast, high or low diastolic pressures, the "lower" number on the reading, were tied to cognitive impairments in subjects who were older, less educated, or not taking blood pressure drugs.

Monitoring and treating high or excessively low blood pressures, "may be critical to the preservation of cognitive function," the researchers conclude.

SOURCE: Hypertension, March 2005.