A new study finds that short-term blood pressure fluctuations over the course of a day or several days can increase the risk of dementia in older adults. The findings suggest that changes in blood pressure may serve as early clinical markers of cognitive impairment. The health risks of high blood pressure are well known, including an increased risk of dementia. But in recent years, blood pressure variability has become increasingly important as a determinant of health risk, thanks to the introduction of wearable non-invasive blood pressure (BP) monitors.
Now, a new study from researchers at the University of South Australia links short-term blood pressure fluctuations over the course of a day, days or weeks to the risk of dementia in older adults.
Daria Gutteridge, lead author of the study, said: "Clinical treatment focuses on high blood pressure but ignores changes in blood pressure. Blood pressure fluctuates over different time periods - short-term and long-term, which appears to increase the risk of dementia and vascular health."
The researchers recruited 70 healthy adults aged 60 to 80 years with no signs of dementia or cognitive impairment. Participants underwent blood pressure monitoring and cognitive testing. The researchers also measured arterial stiffness in the participants' brains and arteries. Arterial stiffness is a well-established cardiovascular risk factor for cognitive impairment and has a strong bidirectional relationship with hypertension.
A quick refresher on blood pressure. Systolic blood pressure, the "top" number on a blood pressure reading measured by a sphygmomanometer, is a measurement of the pressure within the arteries when the heart beats. The bottom "number," diastolic pressure, is the pressure in the arteries when the heart is resting between beats. For example, when the blood pressure is 120/60, 120 is the systolic pressure and 60 is the diastolic pressure.
The researchers found that high systolic blood pressure and short- and long-term diastolic blood pressure variability were associated with poorer cognitive function, independent of mean blood pressure. Higher short-term blood pressure variability was associated with poorer attention and psychomotor speed, whereas daily blood pressure variability was inversely related to executive function.
Higher systolic short-term blood pressure variability is associated with higher arterial stiffness, whereas higher diastolic short-term blood pressure variability is associated with lower arterial stiffness.
"We found that greater blood pressure variability across days and days was associated with cognitive decline," Gutteridge said. "We also found that higher blood pressure changes within systolic blood pressure were associated with higher arterial vascular stiffness. These results suggest that different types of blood pressure changes may reflect different underlying biological mechanisms and that both systolic and diastolic blood pressure changes are important for cognitive function in older adults."
Because hypertension variability is associated with cognitive decline and increased arterial stiffness without clinically associated cognitive impairment, blood pressure variability could be used as a potential early marker or therapeutic target for cognitive impairment, the researchers said.
"Taken together, this study highlights the importance of considering systolic and diastolic blood pressure variability when optimizing blood pressure management as a risk factor for dementia," the researchers said.
The study was published in the journal Brain Circulation - Cognition and Behavior.