Blood pressure swings over 24 hours tied to poorer brain health

Frequent changes in blood pressure could affect cognitive health and contribute to brain changes associated with dementia risk, according to new research from Monash University.

The study, published in Neurology, found that greater variability in blood pressure over a 24-hour period was associated with poorer cognition, including planning, problem solving and memory.

Higher average blood pressure over 24 hours was also associated with greater evidence of vascular brain injury.

While high blood pressure, or hypertension, has long been recognized as a risk factor for cognitive decline, less has been understood about the impact of changes in blood pressure throughout the day and night.

Researchers from the Turner Institute for Brain and Mental Health at Monash’s School of Psychological Sciences used continuous monitoring devices to track the blood pressure of 225 Australians aged between 55 and 80 for 24 hours.

First author Madeline Gibson, a Monash Ph.D. candidate in Clinical Neuropsychology, said the study highlights 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.

“Our study shows that blood pressure is associated with subtle brain changes that can occur long before memory or thinking problems become apparent,” Gibson said.

“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.

“This is especially important in midlife, which may be a key window for protecting brain health and reducing later risk of cognitive decline.”

Senior author Professor Matthew Pase said the study highlights the importance of extended blood pressure monitoring to better understand what is happening for a person over the course of the day and night.

“The research indicates that standard blood pressure readings taken at a doctor’s clinic may not provide the full picture,” Professor Pase said.

“Most people think of blood pressure as a single number taken in a doctor’s clinic, but blood pressure is dynamic.

“Blood pressure rises and falls across the day and night, and those fluctuations may carry important information about brain health.”

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