A woman sits in a wheelchair as a medical professional measures her blood pressure.
The negative health effects of higher blood pressure are more prevalent in blacks, especially related to mental health, kidney disease, stroke and cardiovascular health. (For Spectrum Health Beat)

For seniors and particularly blacks with high blood pressure, lowering it may help keep their minds sharp, a new study suggests.

The association between high blood pressure and the risk for mental decline is well-documented. But the ideal systolic blood pressure for older adults has been less clear-cut, with recommended targets ranging from 150 millimeters of mercury (mm Hg) to 120 mm Hg.

Systolic blood pressure, the amount of pressure exerted by the heart as it pumps blood throughout the body, is the top or first number in a blood pressure reading.

Recent evidence has suggested that while people in general benefit from a systolic blood pressure of 120 mm Hg or less, older adults might fare better with a higher systolic pressure. But this latest study found that lower systolic pressure was best for seniors.

“Lower blood pressure levels are safe and probably better in treating hypertensive older adults,” said lead researcher Dr. Ihab Hajjar, an associate professor of medicine at Emory University School of Medicine in Atlanta.

His team found that participants whose systolic blood pressure was 150 mm Hg or higher were more likely to have declining mental abilities during the 10-year study period than those whose systolic blood pressure was 120 mm Hg or lower.

The effect was even more pronounced in black seniors, Hajjar added.

From 1997 to 2007 Hajjar and colleagues collected data on nearly 1,700 adults aged 70 to 79 who were being treated for high blood pressure and showed no signs of mental decline.

During the study period, participants took tests of mental ability. The researchers found that scores on these tests were linked with the patient’s systolic blood pressure. The higher the systolic number, the more test scores declined.

Moreover, the declines in test scores were greater in blacks with high systolic blood pressures than they were among whites with similar blood pressure readings, the researchers found.

“The negative health effects of higher blood pressure are more prevalent in blacks, especially related to kidney disease, stroke and cardiovascular health,” Hajjar said. “Therefore, it is conceivable that lowering blood pressure in this population would have a far greater impact than other groups for the cognitive effects as well.”

The report was published online in the journal JAMA Neurology.

Dr. Rebecca Gottesman is a professor of neurology and epidemiology in the division of cerebrovascular neurology at Johns Hopkins University in Baltimore.

“Blood pressure control is very important, both for reducing stroke and heart risk, but also for reducing the risk of dementia and cognitive impairment, but we don’t yet know whether initiating antihypertensive therapy in older adults, with the primary purpose of reducing cognitive decline, is actually effective and safe,” she said.

And because it was an observational study, the findings do not prove that lower blood pressure levels in older adults slow thinking declines, she said.

Blood pressure control in general is beneficial, said Gottesman, who wrote an accompanying journal editorial.

Another specialist agreed that the study isn’t the final word on what is the best systolic blood pressure for protecting mental health in older adults.

“We have to be very careful not to read too much into this study,” said Dr. Byron Lee, director of the electrophysiology laboratories and clinics at the University of California, San Francisco.

This is observational research, and there are many other observational studies that suggest it is better to have a higher systolic blood pressure target of 150 mm Hg to 140 mm Hg in older adults, he said.

“This study does remind us, however, that race may be an important factor, which could alter how we treat different patients in the future,” Lee said.