Intensive blood pressure control reduces dementia risk in adults with hypertension

An intensive, four-year blood-pressure intervention significantly reduced the risk of developing dementia among adults with high blood pressure compared to people who received usual care, in a study reported as late-breaking science today at the American Heart Association's Scientific Sessions 2023. The meeting, Nov. 11-13, in Philadelphia, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

In the absence of curative treatments, the primary prevention of dementia through the reduction of risk factors has become a public health priority. Previous observational studies have found that individuals with untreated hypertension have a 42% increased risk of dementia compared with healthy adults, while individuals with treated hypertension have no significant increase in dementia risk compared with healthy adults."

Jiang He, M.D., Ph.D., FAHA, professor of epidemiology and medicine and director of Tulane University's Translational Science Institute in New Orleans

Researchers evaluated the effectiveness of lowering blood pressure on dementia risk among people with high blood pressure. The study was conducted in 326 villages in rural China and included approximately 34,000 adults, ages 40 and older, with untreated blood pressure of 140/90 mm Hg or higher, or 130/80 mm Hg or higher for people at high risk for cardiovascular disease or those currently taking blood pressure medication.

Half of the villages were randomly assigned to a village doctor-led intensive blood pressure intervention strategy, and half of the villages were randomly assigned to usual care. Patients in the usual care villages received their hypertension management from local village doctors or primary care physicians at township hospitals as part of routine health service covered by the China New Rural Cooperative Medical Scheme (a health insurance plan covering approximately 99% of rural residents for basic health-care services in China).

In the intervention group, trained village doctors initiated and adjusted antihypertensive medications based on a straightforward treatment protocol to achieve a goal of lowering systolic blood pressure to less than 130 mm Hg and diastolic blood pressure to less than 80 mm Hg, with supervision from primary care physicians. The stepwise protocol for hypertension management included a treatment algorithm, selection of medication, review of contraindications of medications and, finally, strategies to adjust dose. They also provided discounted and free blood pressure medications to patients and conducted health coaching on lifestyle modifications, home blood-pressure measurement and medication adherence.

At the end of the four-year study period, trained and certified neurologists, who were blinded to randomization assignments, conducted cognitive function assessments or screenings. The final diagnosis of all-cause dementia or cognitive impairment, no dementia was made by an expert adjudication panel, who were also blinded to which intervention the study participants were assigned. Cognitive impairment, no dementia is a broad classification for reduced cognitive functioning that does not meet the criteria for dementia but exceeds the normal, age-related cognitive decline.

The analysis found that the people in the intervention group showed significant improvement in blood pressure control and reduced dementia and cognitive impairment, no dementia compared to those who received usual care. Additional findings:

• The average blood pressure in the intervention group at 48 months was 128/73 mm Hg, compared to 148/81 mm Hg in the usual care group.
• On average, systolic blood pressure decreased by 22 mm Hg and diastolic blood pressure decreased by 9 mm Hg among people in the intervention group compared to usual care.
• People in the intervention group had 15% lower risk of dementia and 16% lower risk of memory impairment compared to the group that received usual care.
• Serious adverse events, such as hospitalizations and death from all causes, were also less frequent in the intervention group.

"This is the first, large, randomized trial to demonstrate that lowering blood pressure is effective in reducing the risk of dementia in people with high blood pressure," He said. "These findings emphasize the importance of widespread adoption of more intensive blood-pressure control to reduce the global burden of dementia."

Study details and background:

• The trial began in May 2018 and ended in March 2023.
• The average age of study participants at enrollment was 63 years old. 61% identified as women, and 39% identified as men; researchers observed similar reductions in blood pressure and dementia risk in women and men.

Study limitations included that researchers did not assess participant's cognitive function during baseline examinations when they enrolled in the trial.

Future studies are needed to examine whether lowering blood pressure will reduce the risk of dementia among adults with high risk for dementia without high blood pressure.

The 2017 ACC/AHA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults classifies stage 1 hypertension as having top and bottom numbers greater than or equal to 130/80 mm Hg and stage 2 hypertension as having top and bottom numbers greater than or equal to 140/90 mm Hg.

According to the American Heart Association's 2023 Statistical Update, nearly half of adults in the U.S. have high blood pressure. The estimated rate of dementia (alone, not including Alzheimer's) in U.S. adults, 65 years of age and older, was 10.5% in 2012, with a rate of 7.3% in males and 12.9% in females, according to the Aging, Demographics and Memory Study, a supplemental study of the long-running Health and Retirement Study.