Researchers at the University of Tennessee Health Science Center (UTHSC) and the Memphis Veterans Affairs (VA) Medical Center were part of the SPRINT MIND (Systolic Blood Pressure Intervention Trial Memory and Cognition IN Decreased Hypertension) multisite clinical trial, which late last month released study findings showing that intensive lowering of blood pressure reduced the risk of mild cognitive impairment (MCI), a known risk factor for dementia.
Mild cognitive impairment causes difficulty with cognition, thinking, remembering, and reasoning that is greater than expected with normal aging. Dementia is a more severe form of loss in cognitive functions that reduces a person's ability to perform everyday tasks. Hypertension, or high blood pressure, is very common in adults age 50 and older and is a leading risk factor for heart disease, stroke, and kidney failure. A growing body of research suggests that hypertension has been identified as a potentially modifiable risk factor for MCI and dementia.
Launched in 2010 by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH), SPRINT enrolled more than 9,300 adults age 50 and older with hypertension who were at a high risk for cardiovascular disease. They were recruited from approximately 102 medical centers and clinical practices throughout the United States and Puerto Rico.
Memphis hosts two SPRINT study sites, one at UTHSC and one at the Memphis VA Medical Center. UTHSC's site, which followed 175 participants, was led by Karen C. Johnson, MD, MPH, principal investigator, College of Medicine Endowed Professor in Women's Health, and professor of Preventive Medicine at UTHSC, and Catherine Womack, MD, associate professor in the Department of Preventive Medicine and co-chief of the Division of Internal Medicine in the College of Medicine at UTHSC.
The Memphis VA Medical Center, which served as a VA Network hub and clinical site, followed 1,660 participants at 25 VA medical centers within the SPRINT Veterans Affairs Clinical Center Network (CCN). William Cushman, MD, chief of Preventive Medicine at the Memphis VA, and professor of Preventive Medicine, Medicine, and Physiology at UTHSC, serves as the principal investigator for the VA Network. Dr. Barry Wall, also from the Memphis VA, is the co-principal investigator for the SPRINT VA Clinical Center Network (CCN) and principal investigator for the VA Memphis SPRINT clinical site that recruited 80 veterans for SPRINT. Linda Nichols PhD, professor, and Jennifer Martindale-Adams, EdD, associate professor in the Department of Preventive Medicine at UTHSC, were VA CCN consultants and also co-principal investigators for the SPRINT MIND study.
The SPRINT MIND study, an essential component of the umbrella SPRINT study, aimed to address whether aggressive blood pressure control would also reduce the risk of developing dementia and cognitive impairment. The study results show that treating blood pressure to a goal of less than 120 mm Hg does not statistically reduce the risk of dementia, but does significantly reduce the risk of developing MCI. Authors of the SPRINT MIND study conclude that this result may have been due to fewer cases of dementia occurring during the study.
"The SPRINT MIND study has shown for the first time that intensive control of blood pressure in older people significantly reduced the risk of developing mild cognitive impairment, a precursor of early dementia," said Dr. Johnson, who also served as the vice chair of the National Steering Committee for the SPRINT study. "This is a very important finding, as it may reduce concerns that many clinicians had that lower systolic blood pressure in older persons might be harmful to their brain."
The Alzheimer's Association has 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 study outcomes. Dr. Nichols is encouraged by the association's commitment to help provide more conclusive study results.
"We are thrilled that the Alzheimer's Association will be working with us to continue to follow SPRINT MIND participants," Dr. Nichols said. "We may be able to determine if intensive blood pressure control will reduce dementia in addition to mild cognitive impairment."
In August 2015, the SPRINT trial was stopped earlier than planned when the beneficial effects of intensive blood pressure management on mortality and cardiovascular disease were discovered. The SPRINT MIND findings provide promise that individuals can take steps to lower their risk of mild cognitive impairment and dementia, and it could be as easy as lowering their blood pressure.
"The fact that cognition and dementia were not worsened and there were even some improvements is very encouraging in light of the impressive improvement in cardiovascular outcomes with intensive blood pressure lowering in SPRINT," Dr. Cushman said.
"These findings provide hope to anyone who is concerned about developing memory problems," Dr. Martindale-Adams said.
SPRINT study findings have already had a world-wide impact on how people define hypertension and how doctors treat hypertension. The American College of Cardiology and the American Heart Association published new blood pressure guidelines in 2017 based on SPRINT data. The SPRINT MIND study results were reported in the Jan. 28, 2019 edition of the Journal of the American Medical Association.