The idea that high blood pressure, or hypertension, can compromise brain health is nothing new, says senior study author Lenore Launer, PhD, chief of the Laboratory of Epidemiology and Population Sciences with the Intramural Research Program at National Institute on Aging. But the results suggest people may need regular blood pressure checks much earlier in life, and much more often, in order to minimize the risk of cognitive problems that can be caused by hypertension. “Especially for younger people it is not sufficient to measure blood pressure once,” Dr. Launer says. “The message from this study is that it is never too early to continually monitor blood pressure and to act if levels are high or continue to increase.” For the study, researchers examined blood pressure trajectories for 853 middle-aged adults based on up to eight measurements taken over 30 years, starting when participants were 18 to 30 years old. Near the end of the follow-up period, all of these participants underwent magnetic resonance imaging (MRI) scans to see whether they had any of the structural changes in their brains that are associated with dementia and cognitive decline. Over time, 187 people, or 21 percent, had consistently low blood pressure. About 23 percent of the participants, however, had moderately elevated blood pressure that gradually increased over time, and another 4 percent of them had high blood pressure that steadily rose during the study period. Compared with people who had low blood pressure throughout the study, individuals who started out with moderately elevated or high blood pressure that increased over time had significantly higher volumes of abnormal white matter in their brain by middle age, the study found. Brain cells that control all of our thought, movement, and bodily functions are the gray matter. The wiring between cells that transmits messages throughout our brain make up the white matter. With increased abnormal white matter, the wiring gets interrupted and messages have to travel longer, more circuitous routes. “The result is that thinking becomes slowed, mental tasks take longer, and some mental activities that would normally require keeping a lot of information in one’s mind and manipulating it — such as comparing two possible complicated options — become impossible,” says Andrew Budson, MD, author of Six Steps to Managing Alzheimer’s Disease and Dementia & Seven Steps to Managing Your Memory and chief of cognitive and behavioral neurology at the Veterans Affairs Boston Healthcare System in Massachusetts. Beyond just damaging white matter, the study also found significantly reduced blood flow to gray matter in people who had moderately elevated or high blood pressure that increased over time. “This means that thinking will not only be slowed, it will be disrupted,” Dr. Budson says. There’s one big caveat: After researchers accounted for use of blood pressure medication, most changes in the brain associated with increasing blood pressure over time were too small to rule out the possibility that they were due to chance. The increased risk of developing abnormal white matter remained significant, but the changes in gray matter did not.
Lifestyle Changes and Blood Pressure Medication Help Protect Brain Health
Several previous studies, however, have linked high blood pressure to an increased risk of dementia and cognitive decline. One study, published in March 2019 in the European Heart Journal, for example, examined data from brain MRIs and health records for almost 9,800 middle-aged and older adults. People in the study who had hypertension also had worse brain health based on abnormalities in gray and white matter, this study found. An older study published in JAMA Neurology tested blood pressure and cognitive performance over 20 years for more than 13,000 middle-aged adults. People with hypertension experienced more cognitive decline over time. However, the magnitude of cognitive decline was much less for people with hypertension who took blood pressure medication. “Hypertension can be effectively treated in most cases and there should be no hesitation in seeking treatment whatever the age,” says Costantino Iadecola, MD, a neurology professor and director of the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine in New York City, who wasn’t involved in the new study. The first and best way to treat high blood or even slightly elevated blood pressure is with lifestyle changes like following a heart-healthy diet, getting plenty of exercise, and maintaining a healthy weight, Budson advises. “If lifestyle modifications are not sufficient to reduce blood pressure to a normal range, medication management is crucial,” Budson says.
