Cerebral oxygenation response to postural change using continuous near-infrared spectroscopy (NIRS) and its association with falls in older adults.

BACKGROUND

Impaired cerebral perfusion during postural changes may contribute to fall risk in older adults. This study used near-infrared spectroscopy (NIRS) as a proxy for cerebral blood flow to investigate the association between cerebral oxygenation responses during postural changes and falls in older adults.

METHODS

We analyzed parameters of oxygenated hemoglobin (OxyHb), deoxygenated hemoglobin (DeoxyHb), total hemoglobin (tHb), and tissue saturation index (TSI) during supine-to-stand and sit-to-stand maneuvers in the PROHEALTH cohort of older adults (n = 30; 23% with positive falls history; mean age 74 ± 7 years). Associations with falls were assessed using logistic regression.

RESULTS

Significant associations with falls history were observed during the supine-to-stand maneuver, despite no significant differences in orthostatic cardiovascular responses. After adjusting for age and sex, lower OxyHb nadir-to-overshoot (OR = 5.20, 95% CI 1.06-25.57), lower TSI overshoot (OR = 1.86, 95% CI 1.04-3.33), and lower TSI initial recovery amplitude (OR = 1.86, 95% CI 1.04-3.34), all within the first minute of standing, were significantly associated with falls history. In addition, lower TSI steady-state values at 60-120 s after standing (OR = 1.56, 95% CI 1.01-2.42) also showed a significant association. No significant associations were observed for any of the parameters during the sit-to-stand maneuver.

CONCLUSIONS

Impaired OxyHb and TSI responses, particularly within the first minute after standing and reduced TSI during sustained impaired recovery (60-120 s), were associated with falls in older adults. Supine-to-stand testing outperformed sit-to-stand testing in identifying cerebral oxygenation impairments. These findings highlight the clinical potential of NIRS as a practical tool for identifying orthostatic cerebral hypoperfusion-related fall risk. Further validation in larger, prospective cohorts is needed.