Irregular blood pressure patterns and dementia-associated brain changes

Hypertension has long been recognised as a risk factor for cognitive decline, yet the impact of blood pressure changes throughout the day has been less understood.

Greater variability in blood pressure over a 24-hour period is associated with poorer cognition, including planning, problem solving and memory; and higher average blood pressure over 24 hours is also associated with greater evidence of vascular brain injury.

This is according to a Monash University study published in Neurology (doi.org/10.1212/WNL.0000000000214935), with findings that are significant given that — according to the university — while high blood pressure, or hypertension, has long been recognised as a risk factor for cognitive decline, the impact of changes in blood pressure throughout the day and night has been less understood.

“Our study shows that blood pressure is associated with subtle brain changes that can occur long before memory or thinking problems become apparent,” said Madeline Gibson, a PhD candidate in Clinical Neuropsychology at Monash and first author on the study. “Even a modest increase in blood pressure variability was linked to lower performance on cognitive tests, equivalent to roughly seven years of additional aging.

“Whether managing blood pressure variability could slow or reverse these brain changes is not yet known. But these findings add to growing evidence that the heart and brain are closely linked,” Gibson said. “This is especially important in midlife, which may be a key window for protecting brain health and reducing later risk of cognitive decline.”

For the study, continuous monitoring devices were used — by researchers from the Turner Institute for Brain and Mental Health at Monash’s School of Psychological Sciences — to track the blood pressure of 225 Australians aged between 55 and 80 for 24 hours, the study highlighting several potential mechanisms through which abnormal blood pressure contributes to dementia, including injury to the brain’s white matter tracts and altered function of the blood–brain barrier, the brain’s protective filtering system.

“The research indicates that standard blood pressure readings taken at a doctor’s clinic may not provide the full picture,” Senior Author Professor Matthew Pase said. “Most people think of blood pressure as a single number taken in a doctor’s clinic, but blood pressure is dynamic,” Pase added. “Blood pressure rises and falls across the day and night, and those fluctuations may carry important information about brain health.”

Image credit: iStock.com/miodrag ignjatovic