Long-term changes in dynamic cerebral autoregulation: a 10 years follow up study

Area of Science:

• Neurology
• Physiology
• Medical Science

Background:

• Dynamic cerebral autoregulation (dCA) shows significant intra- and inter-subject variability.
• Previous research has not adequately characterized long-term intra-subject changes in dCA.
• Understanding dCA stability is crucial for interpreting changes in neurological conditions.

Purpose of the Study:

• To assess long-term intra-subject variability in dCA.
• To characterize time-related changes in dCA by re-evaluating subjects after a decade.
• To investigate if dCA function changes significantly over 10 years in healthy individuals.

Main Methods:

• Longitudinal study of 10 healthy subjects, re-assessed 10 years apart.
• Simultaneous recordings of middle cerebral artery blood flow velocity (CBFV), blood pressure, and heart rate.
• Analysis using frequency-domain (transfer function) and time-domain (step response, Autoregulatory Index - ARI) methods.

Main Results:

• A significant decrease in the Autoregulatory Index (ARI) was observed between 1998 and 2008 (P=0.021).
• Increased coherence at 0.05 Hz (P=0.018) and a significant difference in mean step response (P=0.045) were noted in 2008.
• These findings indicate a decline in dCA function over the 10-year period.

Conclusions:

• This study provides novel insights into intra-subject variability of dCA over a decade.
• Observed declines in frequency and time domain parameters suggest dCA function is not static over long periods.
• The findings necessitate consideration of long-term changes in dCA, potentially independent of aging, in future research.