Volume 13, Issue 10 e202000073
FULL ARTICLE

Diffuse optical assessment of cerebral-autoregulation in older adults stratified by cerebrovascular risk

Ahmed A. Bahrani

Ahmed A. Bahrani

Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky, USA

Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA

Biomedical Engineering Department, Al-Khwarizmi College of Engineering, University of Baghdad, Baghdad, Iraq

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Weikai Kong

Weikai Kong

Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky, USA

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Yu Shang

Yu Shang

Shanxi Provincial Key Laboratory for Biomedical Imaging and Big Data, North University of China, Shanxi, China

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Chong Huang

Chong Huang

Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky, USA

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Charles D. Smith

Charles D. Smith

Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA

Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky, USA

Department of Neurology, University of Kentucky, Lexington, Kentucky, USA

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David K. Powell

David K. Powell

Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky, USA

Neuroscience Department, University of Kentucky, Lexington, Kentucky, USA

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Yang Jiang

Yang Jiang

Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA

Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky, USA

Department of Behavioral Science, University of Kentucky, Lexington, Kentucky, USA

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Abner O. Rayapati

Abner O. Rayapati

Department of Psychiatry, University of Kentucky, Lexington, Kentucky, USA

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Gregory A. Jicha

Gregory A. Jicha

Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky, USA

Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky, USA

Department of Neurology, University of Kentucky, Lexington, Kentucky, USA

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Guoqiang Yu

Corresponding Author

Guoqiang Yu

Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky, USA

Correspondence

Guoqiang Yu, Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506.

Email: [email protected]

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First published: 13 June 2020
Citations: 12

Funding information: American Heart Association, Grant/Award Number: 16GIA30820006; Higher Committee for Education Development in Iraq, Grant/Award Number: Supporting the primary author scholarship; National Institutes of Health, Grant/Award Numbers: 1R01AG062480, 5P30AG028383, R01-HD101508, R21-HD091118; National Science Foundation (NSF), Grant/Award Number: EPSCoR1539068

Abstract

Diagnosis of cerebrovascular disease (CVD) at early stages is essential for preventing sequential complications. CVD is often associated with abnormal cerebral microvasculature, which may impact cerebral-autoregulation (CA). A novel hybrid near-infrared diffuse optical instrument and a finger plethysmograph were used to simultaneously detect low-frequency oscillations (LFOs) of cerebral blood flow (CBF), oxy-hemoglobin concentration ([HbO2]), deoxy-hemoglobin concentration ([Hb]) and mean arterial pressure (MAP) in older adults before, during and after 70° head-up-tilting (HUT). The participants with valid data were divided based on Framingham risk score (FRS, 1-30 points) into low-risk (FRS ≤15, n = 13) and high-risk (FRS >15, n = 11) groups for developing CVD. The LFO gains were determined by transfer function analyses with MAP as the input, and CBF, [HbO2] and [Hb] as the outputs (CA ∝ 1/Gain). At resting-baseline, LFO gains in the high-risk group were relatively lower compared to the low-risk group. The lower baseline gains in the high-risk group may attribute to compensatory mechanisms to maintain stronger steady-state CAs. However, HUT resulted in smaller gain reductions in the high-risk group compared to the low-risk group, suggesting weaker dynamic CAs. LFO gains are potentially valuable biomarkers for early detection of CVD based on associations with CAs.image

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