January 28, 2019
Science Daily/Wake Forest Baptist Medical Center
Intensive control of blood pressure in older people significantly reduced the risk of developing mild cognitive impairment (MCI), a precursor of early dementia, in a clinical trial led by scientists at Wake Forest School of Medicine, part of Wake Forest Baptist Health. However, the National Institutes of Health-supported Systolic Blood Pressure Intervention Trial (SPRINT) Memory and Cognition in Decreased Hypertension (SPRINT MIND) study did not prove that treating blood pressure to a goal of 120 mm Hg or less statistically reduced the risk of dementia. This result may have been due to too few new cases of dementia occurring in the study, the authors noted.
The results were reported in the Jan. 28 edition of the Journal of the American Medical Association.
MCI is defined as a decline in memory and thinking skills that is greater than expected with normal aging and is a risk factor for dementia. Dementia is defined as a group of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person's ability to perform everyday activities.
"As doctors treating older patients, we are encouraged to finally have a proven intervention to lower someone's risk for MCI," said the study's principal investigator, Jeff Williamson, M.D., professor of gerontology and geriatric medicine at Wake Forest School of Medicine. "In the study, we found that just three years of lowering blood pressure not only dramatically helped the heart but also helped the brain."
The objective of SPRINT MIND was to evaluate the effect of intensive blood pressure control on risk of dementia. Hypertension, which affects more than half of people over age 50 and more than 75 percent of those older than 65, has been identified as a potentially modifiable risk factor for MCI and dementia in previous observational studies.
The clinical trial, which enrolled 9361 volunteers, was conducted at 102 sites in the United States and Puerto Rico among adults 50 and older with hypertension but without diabetes or history of stroke. The participating group was 35.6 percent female, 30 percent black and 10.5 percent Hispanic and thus representative of the broader U.S. population.
Participants were randomly assigned to a systolic blood pressure goal of either less than 120 mm HG (intensive treatment) or less than 140 mm HG (standard treatment). They were then classified after five years as having no cognitive impairment, MCI or probable dementia.
"Although the study showed a 15 percent reduction in dementia in the intensively controlled group, we were disappointed that the results did not achieve statistical significance for this outcome," Williamson said. "Last week the Alzheimer's Association agreed to fund additional follow-up of SPRINT MIND participants in the hope that sufficient dementia cases will accrue, allowing for a more definitive statement on these outcomes."
SPRINT was stopped early due to the success of the trial in reducing cardiovascular disease. As a result, participants were on intensive blood pressure lowering treatment for a shorter period than originally planned. The authors concluded that the shorter time may have made it difficult to accurately determine the role of intensive blood pressure control on dementia cases.
Williamson said some caution should be exercised in interpreting the study result both because MCI was not the primary cognitive focus of the trial and because it is not clear what intensive blood pressure control may mean for the longer-term incidence of dementia. Although MCI considerably increases the risk of dementia, this progression is not inevitable and reversion to normal cognition is possible, he said.