Intensive efforts to lower blood pressure — dropping systolic blood pressure, particularly, to lower-than-recommended levels — can reduce a person’s risk of the mild cognitive impairment that may precede Alzheimer’s and of dementia, results of clinical trial show.
“This is the first randomized clinical trial to demonstrate a reduction in new cases of MCI [mild cognitive impairment] alone and the combined risk of MCI plus all-cause dementia,” Jeff Williamson, a professor of internal medicine and epidemiology at Wake Forest School of Medicine, said in a press release.
These results were presented at the recent Alzheimer’s Association International Conference (AAIC 2018) in Chicago.
The Systolic Blood Pressure Intervention Trial (SPRINT) MIND study (NCT01206062) was a large-scale, long-term clinical trial that compared two strategies for managing high blood pressure (hypertension) in older adults: intensive treatment to lower systolic blood pressure to under 120 mm Hg, or a standard of care approach to drop or keep systolic blood pressure to under 140 mm Hg.
Systolic blood pressure (SPB) measures the pressure in blood vessels when the heart beats; it’s the first of two blood pressure values. Normal SBP values are below 120 mm Hg, and those in the 130 – 139 mm Hg range are considered high.
Specifically, SPRINT MIND explored if an intensive treatment approach would also lower the risk of MCI — an intermediate clinical stage that does not yet meet the criteria for dementia — and that of dementia, while possibly also lowering the volume of age-associated lesions in the brain’s white matter, which is made of nerve fibers.
It enrolled 9,361 adults, ages 50 or older (mean age 67.9; 35.6% women), with hypertension (defined as SPB greater than 130 mm Hg plus one other cardiovascular disease risk factor) but without dementia starting in October 2010.
Antihypertensive medications used included different classes of diuretics as well as beta blockers. Participants were assessed monthly for the first three months, and every three months thereafter. A total of 8,626 (92.1%) participants completed at least one follow-up assessment of cognition.
After one year, those given intensive treatment had a mean systolic blood pressure of 121.4 mmHg, while mean SBP for those in the standard treatment group was 136.2 mmHg. Blood pressure treatment was stopped in 2015 after a median follow-up of 3.26 years, but cognitive assessments continued through June 2018.
Results showed that, besides lessening a person’s risk of cardiovascular disease, intensive blood pressure treatment was associated with a statistically significant 19% reduction in new cases of MCI. The combination of MCI plus probable all-cause dementia was 15% lower in the intensive group compared to people on standard treatment.
Of note, the rate of overall serious adverse events was similar between the two groups, although adults undergoing intensive treatment had significantly more serious adverse events (4.7% vs. 2.5%) — including hypotension (low blood pressure), electrolyte abnormalities, and acute kidney injury — thought possibly or definitely related to treatment.
Preliminary results on brain white matter lesions were given in a separate but related AAIC 2018 presentation, and showed an increase — expected with aging — in total white matter lesion volume in both treatment groups. But this increase was significantly less pronounced in people under intensive blood pressure treatment.
Lesions were measured in 673 SPRINT MIND participants using brain magnetic resonance imaging (MRI), which assessed total brain volume and white matter lesion volume, an indicator of small vessel disease that’s associated with a higher risk of stroke, dementia and death.
“These results support the need to maintain well-controlled blood pressure, especially for persons over the age of 50,” Williamson said. “A particular strength of SPRINT-MIND is that 30 percent of the participants were African American and 10 percent were Hispanic.”
This data is in line with recent evidence of a drop in new cases of dementia in developed Western cultures. That positive change may be due to better efforts to control of cardiovascular disease risk factors that include medications, a drop in smoking, and a greater awareness of the importance of a healthy lifestyle, said Maria C. Carrillo, PhD, chief science officer for Alzheimer’s Association.
“This study shows more conclusively than ever before that there are things you can do — especially regarding cardiovascular disease risk factors — to reduce your risk of MCI and dementia,” Carrillo said.
She also suggested that — similar to heart disease treatment — future approaches to lowering MCI and dementia could include a combination of medications and lifestyle changes.
“These new blood pressure findings raise our level of anticipation for the U.S. POINTER Study, which includes managing cardiovascular disease risk factors as part of the multi-component lifestyle intervention,” she added.
U.S. POINTER is a two-year trial, funded by the Alzheimer’s Association, to test whether lifestyle interventions — physical exercise, cognitive and social stimulation, nutritional counseling, and better health self-management — can preserve cognitive function in older adults at risk for cognitive decline.