According to research, MRI scans of patients who received more intensive high blood pressure treatment show a positive change in their brain structures that clear toxins and other byproducts. The study, whose results will be presented at the American Stroke Association’s International Stroke Conference 2023, checks whether intensive blood pressure treatment slows or reverses structural changes linked with the volume of the brain’s areas around blood vessels, known as perivascular spaces, which clear toxins. As people get older or develop cardiovascular problems, the perivascular spaces enlarge.
From 2010 to July 2016, the researchers studied the brain MRI scans of 658 participants, part of the SPRINT-MIND MRI substudy, with high blood pressure but no previous diabetes diagnoses, dementia, or stroke. In the follow-up conducted 3.9 years later, 243 people in the intensive treatment group and 199 people in the standard treatment arm underwent pre- and post-MRI scans to analyze the percentage of the brain occupied by perivascular spaces.
The screening took place at seven MRI sites across the US: Boston University, Vanderbilt University, University of Miami, University of Alabama, Case Western Reserve University, University of Pennsylvania, and Wake Forest University. MRI scans in the study’s initial phase indicated that the percentage of the brain occupied by perivascular spaces was higher in older patients with increased white matter hyperintensities volume. These patients also had another sign of aging and declining brain health in common: brain atrophy.
“If the brain cannot properly clear toxins and metabolic byproducts, they will accumulate and may contribute to the development of dementia,” said Kyle Kern, MD, MS, lead author of the study. “However, high blood pressure over the long term stiffens arteries, impairing function and the ability to clear toxins, resulting in enlargement of perivascular spaces,” he added.
Once the participants’ age, sex, and the screening site were controlled, the study displayed that despite both blood pressure treatments groups having similar perivascular spaces volume, the volume had reduced significantly in the intensive treatment group after four years of high blood pressure treatment; no changes were recorded in the standard treatment group.
According to the original SPRINT-MIND MRI study, intensive blood pressure control could potentially slow white matter hyperintensities accumulation. However, the substudy indicated that it might play a significant role in reversing the effects of high blood pressure on perivascular spaces. “Previous research has confirmed that effective blood pressure control is important for brain health. Our secondary analysis findings from SPRINT-MIND MRI suggest that intensive blood pressure control may be beneficial by reducing damage to the brain’s toxin and byproduct clearance pathway,” said Kern.
Since the study is limited to the available data and subsequent results, it excludes the scope of determining whether changes in the perivascular spaces positively affect thinking ability or if it is simply a byproduct of blood pressure treatment without a cause-and-effect relationship to cognitive functions.
Next, the SPRINT-MIND trial focused on finding the relationship between perivascular spaces and cognitive decline. The trial included high-quality cognitive function assessment multiple times to understand the role of perivascular spaces in the impact of intensive blood pressure control on cognitive decline.
The American Heart Association states that the average blood pressure is below 120/88 mm HG. If the systolic pressure is 120-129 mm HG and the diastolic pressure is under 80 mm HG, the blood pressure is high. This finding confirms the possibility of reducing perivascular space size by lowering the intensive systolic blood pressure, according to Philip B. Gorelick, MD, MPH, FAHA, chair of the American Heart Association’s Stroke Brain Health Science Subcommittee.
