Global brain venous oxygenation is associated with cardiorespiratory fitness in older adults

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AbstractBackgroundT2‐Relaxation‐Under‐Spin‐Tagging (TRUST) is an MRI technique which allows for the measurement of brain blood oxygenation. Global venous oxygenation has been shown to decrease over the course of life and may prove useful as a measure of brain aging. No studies to date have examined the association between cardiovascular fitness and brain venous oxygenation.MethodGlobal venous oxygenation (Yv) and cardiorespiratory fitness were measured in sixteen older adults. Yv was measured from voxels within the superior sagittal sinus (SSS) using the TRUST sequence. The four voxels with the highest measured signal had their intensities averaged within each volume of the sequence. These values were fitted to an exponential function to yield a quantitative T2 and an estimate of Yv. Cardiorespiratory fitness was measured as the VO2 peak (mL/kg/min) during a cardiopulmonary exercise test to maximal capacity or volitional termination following the Cornell modified Bruce protocol.ResultUsing a linear regression with age and sex as covariates (F = 4.410, p = .31), Yv was shown to associate significantly with peak VO2 (b = .444, p = .020). Yv did not differ between male and female participants (t = 1.758, p = .101), and did not appear to associate independently with age (R = .182, p = .499). However, our sample was small and only included older adults.ConclusionThis study shows for the first time that whole body cardiorespiratory fitness is associated with global brain venous oxygenation. Future work will examine the utility of this neuroimaging biomarker to monitor changes in fitness with measures of cognitive aging