Older adults whose blood pressure jumps up and down from one heartbeat to the next may face a greater risk of brain shrinkage and nerve cell injury, new research suggests.
The study, led by the USC Leonard Davis School of Gerontology and published in the Journal of Alzheimer’s Disease, found that these short-term fluctuations — known as “dynamic instability” — were linked to loss of brain tissue in regions critical for memory and thinking, as well as to blood markers that indicate nerve cell damage.
“Our findings show that even when average blood pressure is normal, instability from one heartbeat to the next may place stress on the brain,” said USC Leonard Davis School Professor of Gerontology and Medicine Daniel Nation, senior author of the study.
“These moment-to-moment swings appear to be associated with the same kinds of brain changes we see in early neurodegeneration.”
While high blood pressure has long been recognised as a risk factor for dementia, this new research shines a light on a lesser-known threat — how much your blood pressure rises and falls in short bursts.
As part of the study, researchers looked at 105 healthy adults aged 55 to 89 who were living independently and had no major neurological diseases.
During MRI scans, each participant’s blood pressure was tracked beat by beat using a finger cuff device over a seven-minute period.
The team then compared those readings with brain imaging and blood samples.
Two key measures were used:
Average Real Variability (ARV) — which shows how much systolic blood pressure (the top number in a reading) changes between heartbeats.
Arterial Stiffness Index (ASI) — which indicates how flexible or stiff the arteries are as they respond to pressure changes.
Together, these measures reflect “blood pressure dynamic instability” — in other words, how steady or unsteady blood flow is over short periods.
Participants who had both high ARV and high ASI — meaning their blood pressure fluctuated more and their arteries were stiffer — showed smaller volumes in the hippocampus and entorhinal cortex, two areas of the brain vital for learning and memory and among the first affected by Alzheimer’s disease.
Blood tests also revealed higher levels of neurofilament light (NfL), a marker that rises when nerve cells are damaged.
Crucially, these findings held true even after accounting for participants’ age, sex, and average blood pressure — meaning it’s not just high pressure that’s a problem, but how much it swings.
“Blood pressure isn’t static; it’s always adapting to the body’s needs,” Nation explained.
“But as we age, that regulation can become less precise. This study suggests that excessive fluctuations could be a sign of vascular aging that contributes to brain injury.”
Lead author Dr Trevor Lohman, research assistant professor of neurology and gerontology at USC, said the findings could change how doctors think about heart and brain health.
“Traditionally, we’ve focused on lowering average blood pressure numbers,” Lohman said.
“But this study suggests we should also be looking at how stable blood pressure is from moment to moment. Reducing these fluctuations could help protect the brain, even in people whose average readings look fine.”
The researchers hope future studies will explore whether treatments that stabilise blood pressure — such as adjusting medication timing, regular exercise, or managing stress — could help slow brain ageing and reduce dementia risk.
However, they also note that this was a cross-sectional study, meaning it shows a connection but not direct cause and effect. Larger, long-term studies will be needed to confirm whether reducing blood pressure swings can indeed protect brain health.
The message for older adults is simple: looking after your heart health is also looking after your brain health.
As Lohman put it, “Our results underscore how closely connected the heart and brain are. Maintaining steady, healthy blood flow could be one of the best ways to support brain health as we age.”
IMPORTANT LEGAL INFO This article is of a general nature and FYI only, because it doesn’t take into account your personal health requirements or existing medical conditions. That means it’s not personalised health advice and shouldn’t be relied upon as if it is. Before making a health-related decision, you should work out if the info is appropriate for your situation and get professional medical advice.