Older Adults’ Drop in Cerebral Oxygenation on Standing Correlates With Postural Instability and May Improve With Sitting Prior to Standing

• Published in: The journals of gerontology. Series A, Biological sciences and medical sciences Biological sciences and medical sciences, 2021-06, Vol.76 (6), p.1124-1133
• Main Authors: Fitzgibbon-Collins, Laura K, Heckman, George A, Bains, Ikdip, Noguchi, Mamiko, McIlroy, William E, Hughson, Richard L
• Format: Article
• Language: English
• Subjects: Blood flow; Blood pressure; Cerebral blood flow; Exercise; Falls; Hypotension; Infrared spectroscopy; Instability; Older people; Oxygenation; Posture
• ISSN: 1079-5006; 1758-535X
• DOI: 10.1093/gerona/glaa194

Abstract Background Impaired blood pressure (BP) recovery with orthostatic hypotension on standing occurs in 20% of older adults. Low BP is associated with low cerebral blood flow but mechanistic links to postural instability and falls are not established. We investigated whether posture-related reductions in cerebral tissue oxygenation (tSO2) in older adults impaired stability upon standing, if a brief sit before standing improved tSO2 and stability, and if Low-tSO2 predicted future falls. Method Seventy-seven older adults (87 ± 7 years) completed (i) supine–stand, (ii) supine–sit–stand, and (iii) sit–stand transitions with continuous measurements of tSO2 (near-infrared spectroscopy). Total path length (TPL) of the center of pressure sway quantified stability. K-cluster analysis grouped participants into High-tSO2 (n = 62) and Low-tSO2 (n = 15). Fall history was followed up for 6 months. Results Change in tSO2 during supine–stand was associated with increased TPL (R = −.356, p = .001). When separated into groups and across all transitions, the Low-tSO2 group had significantly lower tSO2 (all p < .01) and poorer postural stability (p < .04) through 3 minutes of standing compared to the High-tSO2 group. There were no effects of transition type on tSO2 or TPL for the High-tSO2 group, but a 10-second sitting pause improved tSO2 and enhanced postural stability in the Low-tSO2 group (all p < .05). During 6-month follow-up, the Low-tSO2 group had a trend (p < .1) for increased fall risk. Conclusions This is the first study to show an association between posture-related cerebral hypoperfusion and quantitatively assessed instability. Importantly, we found differences among older adults suggesting those with lower tSO2 and greater instability might be at increased risk of a future fall.