Dynamic cerebral autoregulation in the old using a repeated sit-stand maneuver

Area of Science:

• Neuroscience
• Physiology
• Gerontology

Background:

• Cerebral autoregulation (CA) is crucial for maintaining brain blood flow, especially in older adults.
• Assessing CA in elderly individuals (>70 years) presents challenges due to potential limitations in existing methods.
• Simple, nonobtrusive methods are needed to evaluate CA in this demographic.

Purpose of the Study:

• To determine the feasibility and reproducibility of a repeated sit-stand maneuver for assessing CA.
• To evaluate the effectiveness of this maneuver in generating a significant hemodynamic challenge in healthy older adults.
• To compare the CA assessment using sit-stand maneuvers with spontaneous oscillations.

Main Methods:

• 27 healthy older adults (>70 years) underwent 5 minutes of rest and repeated sit-stand maneuvers (0.05 Hz and 0.1 Hz).
• Blood pressure (photoplethysmography) and middle cerebral artery blood flow velocity (transcranial Doppler) were continuously measured.
• Measurements were repeated after 3 months in 11 subjects to assess reproducibility.

Main Results:

• Sit-stand maneuvers induced significant periodic oscillations in blood pressure and flow (e.g., 0.05 Hz increased power spectral density by 16.3 (mmHg)2 and 14.5 (cm/s)2).
• Transfer function coherence increased significantly during maneuvers (0.05 Hz: 0.46 to 0.60; 0.1 Hz: 0.56 to 0.76), enabling more confident CA assessment.
• Despite increased coherence, the reproducibility of CA assessment was not improved.

Conclusions:

• Repeated sit-stand maneuvers are a feasible method for investigating CA in older adults.
• The maneuver provides a stronger and more clinically relevant hemodynamic challenge for CA compared to spontaneous oscillations.
• This technique offers a valuable tool for assessing cerebral blood flow regulation in the elderly.