Blood Pressure Control Reverses Expansion of Perivascular Spaces in the Aging Brain
Study data here shows that age-related enlargement of perivascular spaces in the brain is to some degree driven by raised blood pressure, and reversible given control of blood pressure. As the researchers note, this enlargement is a part of the issues that lead to a reduced clearance of metabolic waste from the brain in later life. This reduced clearance is likely an important factor in the development of neurodegenerative conditions. All told, the raised blood pressure of hypertension is one of the more important ways in which deeper causes of aging are converted to tissue dysfunction and outright structural damage throughout the body. Even without addressing the underlying causes, forcing a reduction in blood pressure via antihypertensive drugs reduces mortality and risk of a range of age-related conditions.
Among people who received more intensive treatment for high blood pressure, evaluations of MRI scans indicated a positive change in brain structures involved in its ability to clear toxins and other byproducts. The study is the first to examine whether intensive blood pressure treatment may slow, or reverse structural changes related to the volume of the brain's perivascular spaces, areas of the brain around the blood vessels that are involved in the clearance of toxins and other byproducts. These areas tend to enlarge as people get older or have more cardiovascular risk factors.
"If the brain cannot properly clear toxins and metabolic byproducts, they will accumulate and may contribute to the development of dementia. Some research has proposed that the pulsations of the cerebral arteries with each heartbeat help to drive the clearance of these toxic brain byproducts in the perivascular spaces. However, high blood pressure over the long term stiffens arteries, impairing function and the ability to clear toxins, resulting in enlargement of perivascular spaces."
The researchers analyzed brain MRI scans for 658 participants (average age of 67 years, 60% women) of the SPRINT-MIND MRI substudy. After an average 3.9-year follow-up period, 243 people in the intensive treatment group (systolic blood pressure goal of 120 mm Hg) and 199 people in the standard treatment arm (systolic blood pressure goal of 140 mm Hg) had pre- and post-MRI scans that were analyzed for the percentage of brain tissue taken up by perivascular spaces.
In MRI scans taken when the study began, the percentage of brain tissue occupied by perivascular spaces was higher among the patients who were older and had a greater volume of white matter hyperintensities. After controlling for age and sex of the participants, at the start of the study, the volume of perivascular spaces was similar among participants in both blood pressure treatment groups. After almost 4 years of high blood pressure treatment, the volume of perivascular spaces had decreased significantly in the intensive treatment group but did not change in the standard treatment group.