Does Intensive Blood Pressure Control Reduce Dementia?

In dementia research, hope for a cure may seem elusive.  So, it’s noteworthy when study results show something that can help older adults reduce their risk of minor cognitive problems. A large new study found that intensive treatment for lowering high blood pressure did not significantly reduce dementia risk. But what it did do was have a measurable impact on mild cognitive impairment (MCI), which is a well-established precursor of dementia. Study participants who received intensive treatment for their hypertension were less likely than those who received standard blood pressure treatment to develop minor memory and thinking problems, typical of MCI.

The SPRINT MIND study, published on January 28, 2019  in JAMA, was an integral aspect of the initial design for SPRINT, a large, randomized clinical trial of intensive blood pressure lowering on cardiovascular and renal disease.  The National Institutes of Health funded both of these studies.

Dementia and Mild Cognitive Impairment – A Public Health Challenge

“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 [of the SPRINT MIND study] 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 with cognition, thinking, remembering, and reasoning, than normal for people their age. 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. It is a leading risk factor for heart disease, stroke and kidney failure. Plus, a growing body of research suggests that high blood pressure may increase risk for dementia later in life.

The SPRINT Study

This current research was part of a large cardiovascular study called SPRINT that began in 2010. More than 9,300 racially and ethnically diverse adults age 50 years and older comprised the sample. Participants had hypertension defined as a systolic blood pressure (top number) from 130 t0 180. None of the participants had diabetes or a stroke history.

The ultimate goal of the SPRINT study was to determine if people with hypertension would do better if treated intensively enough that their blood pressure dropped below 120 compared to the people receiving the standard treatment which brought their blood pressure to the 140 mark.  The study was so successful that it was stopped after 3.3 years of treatment. It was found that the participants more intensively treated had significantly lower risk of cardiovascular disease and mortality. However, assessment for the development of dementia and MCI continued for the full planned five years. Read more about the SPRINT study here.

The SPRINT MIND Study

The SPRINT MIND study is the cognitive piece of the original SPRINT study. 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. Participants with high blood pressure but no history of stroke or diabetes, at the trial’s start, underwent cognitive assessments. Over 91 percent of these participants had at least one follow up. Participants were classified into one of three categories: no cognitive impairment, MCI, or probable dementia.

The primary results of this analysis found no statistically significant difference between standard and intensive treatment in the proportion of participants diagnosed with dementia. Fewer patients developed “probable dementia” possibly because the participants were treated for a shorter period than originally planned. In other words, participants were no longer monitored about whether they followed the intensive blood pressure treatments.  The authors concluded that 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.

Yet, the secondary results of the SPRINT MIND study suggested that the intensive treatment reduced the risk of MCI. It also reduced the combined risk of MCI and 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.

What This Study Means For You

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.

“This is a landmark study in that it is the first trial of its size and scope to look at a modifiable risk factor for dementia and MCI,” said Lenore J. Launer, Ph.D., a senior investigator in the NIA Laboratory of Epidemiology and Population Sciences and co-author of the paper. Launer further stated the study had a carefully designed hypothesis and used approved appropriate tools to assess dementia and MCI. It was blinded for diagnosis, and got a good sample of older people.

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 physician to decide the best blood pressure goals for themselves. Consultations should also include determinations on how to reach those goals. Suggestions might include introducing lifestyle changes such as diet and exercise or lifestyle changes in conjunction with 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.”

Article adapted from: https://www.nia.nih.gov/news/does-intensive-blood-pressure-control-reduce-dementia