Intensive Blood Pressure Control and Dementia

By Jane Farrell

Intensive blood pressure lowering has an impact on mild cognitive impairment (MCI) but doesn’t lessen dementia risk, according to the final results of two large, federally funded studies.

The peer-reviewed findings of the Systolic Blood Pressure Intervention Trial (SPRINT) Memory and Cognition in Decreased Hypertension (SPRINT MIND) were published on Jan. 28, 2019 in the Journal of the American Medical Association.

SPRINT MIND was an integral aspect of the initial design for SPRINT, a large, randomized clinical trial of intensive blood pressure lowering on cardiovascular and renal (kidney) disease; both were funded by the federal National Institutes of Health (NIH).

“Dementia continues to be a large public health challenge, and based on the primary results of this study, we still have yet to find an intervention strategy proven to reduce the risk of dementia,” said Richard J. Hodes, M.D., director of the National Institute on Aging (NIA), part of NIH and the lead institute on Alzheimer’s research. “Nevertheless, the secondary results showing that intensive lowering of blood pressure may reduce risk for MCI, a known risk factor for dementia, gives us additional avenues to explore on the path to prevention.”

MCI is a condition in which people have more difficulty than normal for their age with cognition, thinking, remembering, and reasoning. Dementia is a more severe form of loss in cognitive functions that interferes with daily life. Alzheimer’s disease is the most common type of dementia. High blood pressure, or hypertension, is very common in persons over the age of 50, and a growing body of research suggests that it may increase risk for dementia later in life.

The participants in SPRINT were adults 50 years and older at high risk for cardiovascular disease. Results of the SPRINT trial, which ended early, showed that intensive blood pressure control, i.e., a systolic (upper number) blood pressure target of less than 120 mmHg (<120 mmHg), compared to a standard target of less than 140 mmHg (<140 mmHg), reduced cardiovascular events and overall mortality. Between November 2010 and March 2013 more than 9,300 participants were randomized to the two target groups with nearly 4,700 in each group. In August 2015, the SPRINT trial was stopped after 3.3 years of treatment when the major beneficial effects of intensive blood pressure management on mortality and cardiovascular disease were discovered. The assessment for development of dementia and MCI continued for the full planned five years.

There currently are no proven interventions that prevent or delay mild cognitive impairment or dementia.

SPRINT MIND aimed to address whether intensive blood pressure control would also reduce the risk of developing dementia and cognitive impairment over the ensuing five years. Cognitive assessments were given to participants who had high blood pressure but no history of stroke or diabetes at the start of the trial, and over 91 percent had at least one follow up. Participants were classified into one of three categories: no cognitive impairment, MCI, or probable dementia.

The SPRINT MIND Research Group, including corresponding author Jeff D. Williamson, M.D., M.H.S., from Wake Forest School of Medicine, Winston-Salem, North Carolina, noted that the primary results of this analysis found no statistically significant difference between standard and intensive treatment in the proportion of participants that were diagnosed with dementia. The study, however, had fewer cases of dementia than expected. Nevertheless, the secondary results suggested that the intensive treatment reduced the risk of MCI and the combined risk of MCI and dementia. Due to the success of the SPRINT trial on the cardiovascular outcomes, the study intervention was stopped early; as a result, participants were treated for a shorter period than originally planned. The shorter time and the unexpected fewer cases of dementia may have made it difficult to determine the role of intensive blood pressure control on dementia, the authors said.

They emphasized that this is the first randomized clinical trial demonstrating that an intervention significantly reduces the occurrence of MCI, which is often a precursor for dementia. An important conclusion is that the intensive lowering of systolic blood pressure to <120 mmHg target—which reduces the risk of cardiovascular events and mortality—is safe for the brain.

The authors noted that there currently are no proven interventions that prevent or delay the incidence of MCI or dementia. Therefore, people should consult with their healthcare providers to decide the best blood pressure goals for themselves and to determine how to reach those goals (for example, introducing lifestyle changes such as diet and exercise; or lifestyle changes with addition of blood pressure medications).

These results also emphasize the connection between vascular health and the brain. In 2016, the NIH launched the Mind Your Risks campaign to make the public more aware of that link. For more information, click here.