Fluctuating blood pressure increases risk of dementia in older people

A new study has found that short blood pressure fluctuations – across a day or several days – increase the risk of dementia in older adults. The findings suggest that blood pressure variability could serve as an early clinical marker of cognitive impairment.

The health risks of having high blood pressure, or hypertension, are well known and include an increased risk of developing dementia. In recent years, though, thanks to wearable, non-invasive blood pressure (BP) monitors, BP variability has gained importance as a determinant of health risk.

Now, a new study by researchers at the University of South Australia has linked short blood pressure fluctuations – over a day, several days or weeks – with the risk of dementia in older adults.

“Clinical treatments focus on hypertension while ignoring the variability of blood pressure,” said Daria Gutteridge, lead author of the study. “Blood pressure can fluctuate across different time frames – short and long – and this appears to heighten the risk of dementia and blood vessel health.”

The researchers recruited 70 healthy adults aged between 60 and 80 with no signs of dementia or cognitive impairment. Participants had their BP monitored and underwent a cognition test. 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 BP. Systolic BP, the ‘top’ number, is a measure of the pressure in the arteries when the heart beats. The ‘bottom’ number, diastolic BP, is the pressure in the arteries when the heart rests between beats. Therefore, in a BP of 120/60, 120 is the systolic BP, and 60 is the diastolic.

The researchers found that high systolic BP as well as short- and long-term diastolic BP variability was associated with poorer cognitive functioning, independent of the mean BP. Higher short-term BP variability was associated with poorer attention and psychomotor speed, whilst day-to-day BP variability was negatively linked with executive functioning.

Higher systolic short-term BP variability was associated with higher arterial stiffness, and higher diastolic short-term BP variability was linked with lower arterial stiffness.

“We found that higher blood pressure variability within a day, as well as across days, was linked with reduced cognitive performance,” Gutteridge said. “We also found that higher blood pressure variations within the systolic BP were linked with higher blood vessel stiffness in the arteries. These results indicate that the different types of BP variability likely reflect different underlying biological mechanisms and that systolic and diastolic blood pressure variation are both important for cognitive function in older adults.”

Because high BP variability was associated with lower cognitive performance and increased arterial stiffness in the absence of clinically relevant cognitive impairment, the researchers say BP variability could be used as a potential early marker of cognitive impairment or a treatment target for cognitive impairment.

“Overall, this study has highlighted the importance of taking the variable nature of systolic and diastolic BP into consideration, when optimizing the management of BP as a dementia risk factor,” the researchers said.

The study was published in the journal Cerebral Circulation – Cognition and Behavior.

Source: University of South Australia