Intensive lowering of high BP cuts the risk for mild cognitive impairment (MCI) but does not significantly reduce dementia risk, according to results from the Systolic Blood Pressure Intervention Trial Memory and Cognition in Decreased Hypertension (SPRINT-MIND) published in the journal JAMA.
SPRINT MIND secondary results are the first to show an intervention that significantly reduces the occurrence of MCI, which is a well-established precursor of dementia. The findings, although were not definitive on reducing the risk for dementia, however, perhaps because the trial wasn’t long enough, note the researchers.
“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, 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 the risk for MCI, a known risk factor for dementia, gives us additional avenues to explore on the path to prevention.”
MCI is a condition characterized by difficulty with thinking, remembering, cognition, and reasoning. Dementia is a more severe form of loss in cognitive functions that interfere with daily life. Alzheimer’s disease is the most common type of dementia. Hypertension, or high blood pressure, commonly seen in people above the age of 50, is a leading risk factor for heart disease, stroke, kidney failure, and a growing body of research suggests its role in increasing dementia risk later in life.
SPRINT trial involved patients 50 years and above at high risk for cardiovascular disease. Results of the trial, that ended early showed that intensive blood pressure control, i.e., a systolic 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. Assessment for development of dementia and MCI continued for the full planned five years.
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.
- During a total median follow-up of 5.11 years, adjudicated probable dementia occurred in 149 participants in the intensive treatment group vs 176 in the standard treatment group (7.2 vs 8.6 cases per 1000 person-years).
- Intensive BP control significantly reduced the risk of mild cognitive impairment (14.6 vs 18.3 cases per 1000 person-years) and the combined rate of mild cognitive impairment or probable dementia (20.2 vs 24.1 cases per 1000 person-years).
The SPRINT MIND Research Group, including corresponding author Jeff D. Williamson, the 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 fact that there was still an MCI result when the study was cut short makes these results encouraging,” explained Laurie Ryan, Ph.D., chief of the Dementias of Aging Branch in the NIA Division of Neuroscience.
The authors emphasized that this is the first randomized clinical trial demonstrating that an intervention significantly reduces the occurrence of MCI, which is an established risk factor and often a precursor for dementia. An important conclusion from this research 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 the addition of blood pressure medications).
“This study is in line with where the field of dementia research is going: preventing memory loss earlier,” added Ryan, who is also the program lead for SPRINT MIND. “Much like we have research-based interventions for heart health and cancer prevention, we hope to have guidance based on this and subsequent studies that will more definitively show how to slow or even stop dementia well before symptoms appear.”
For further reference log on to 10.1001/jama.2018.21442