How hypertension affects memory.

People suffering from mild hypertension often lag behind those with normal blood pressure on several general tests of memory and learning. But scientists have yet to pin down the specific components of memory that prove most sensitive to elevated blood pressure.

A new study suggests that the memory deficits displayed by hypertensives revolve around tasks requiring speedy mental manipulations and retrieval of just-learned information. The scores of hypertensives on such tests do not necessarily reflect any problems in performing routine daily activities, but the statistically strong disparity between hypertensives and controls with normal blood pressure cannot be attributed to differences in age, education, or psychological health, according to James A. Blumenthal, a psychologist at Duke University Medical Center in Durham, N.C., and his colleagues.

Blumenthal's group recruited 100 white adults ranging in age f rom 29 to 59 years old. Of that number, 68 met the criterion for hypertension, defined as blood pressure between 140/90 millimeters of mercury (mm Hg) and 180/105 mm Hg. The remaining volunteers displayed normal blood pressure readings, averaging 111/72 mm Hg.

Participants completed eight tests that, the researchers assert, encompass three dimensions of memory: rapid information processing and recall of just-learned material, verbal memory, and memory for shapes. Hypertensives performed more poorly than controls only on measures tapping into the first dimension, Blumenthal and his associates contend in the January-February PSYCHOSOMATIC MEDICINE.

For instance, immediately after studying either two, four, or six digits shown on a video screen, hypertensives took longer to indicate whether a single digit presented later on the screen had been part of the original set. They also required more time to draw a line connecting a series of letters and numbers in sequence (1-A, 2-B, and so on).

The ways in which sustained hypertension may alter brain function and thus subtly interfere with mental activity remain unknown, the researchers note.