Age, sex and blood pressure medications impact brain blood oxygen during standing

Posted on: 09 September 2022

New research from The Irish Longitudinal Study on Ageing (TILDA) examined how blood oxygen levels in the brain (“cerebral oxygenation”) are affected when a person stands up. Blood flow to the brain provides oxygen and nutrients for normal function. A reduced supply has been associated with adverse events such as falls, depression and cognitive decline.

The group has previously studied the blood pressure response to standing, but in this study - published in the journal Experimental Gerontology - cerebral oxygenation was examined.

The study used data from 2,764 community-dwelling participants. The size of the study enabled researchers to account for a range of confounding factors.

KEY FINDINGS

• Women experienced a smaller drop in cerebral oxygenation compared to men.
• Women took longer to return to their normal level.
• Older age groups had a larger initial drop in cerebral oxygenation and impaired stabilisation.
• Those taking blood pressure lowering medications took longer to recover.
• Blood pressure levels also only partly explained some of the differences that we found.

Louise Newman is the lead author of the study and Research Assistant in Medical Gerontology at Trinity. She said:

“We know that age affects how quickly blood pressure recovers when a person stands up, but we didn’t know if it was the same for cerebral oxygenation.

"We used novel equipment, near-infrared spectroscopy, to measure the change in blood oxygen in the brain during a standing task. We found that women experienced a smaller drop in cerebral oxygenation compared to men, but women took longer to return to their normal level. We also found that those taking anti-hypertensive medications took longer to recover.

However, there were no differencesin the cerebral oxygenation response in those who told us they felt dizzy, light-headed or unsteady when standing up. Blood pressure levels also only partly explained some of the differences that we found.”

She explained: “The study highlights the need for standing cerebral blood measures to be assessed in older patients, regardless of symptoms”.

Professor Rose Anne Kenny, TILDA’s Principal Investigator, said:

“Brain cells survive and function according to how much oxygen they receive and how quickly the cells and circulation can clear toxins from the brain cells. We stand up 30-50 times per day and each time our bodies must react quickly to ensure that the flow of blood and therefore oxygen is kept constant. For the first time in such a large adult study we have measured such brain blood flow when TILDA participants stood up and demonstrated that the ability to react quickly and maintain flow is impaired year on year over 50 years.

Furthermore, men and women react differently. Muscle strengthening exercises and other interventions can change in a beneficial way these responses, so early recognition of problems, using this novel technology, should trigger treatments and lifestyle behaviour changes. As a result of this research, we have started to use the new technology in clinical settings to improve patient management.“

The study, Age and sex related differences in orthostatic cerebral oxygenation: Findings from 2764 older adults in the Irish Longitudinal Study on Ageing, is published in the journal Experimental Gerontology and is freely available to all online.

It can be read on the publisher’s website.

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