Age-Related Changes in Cortical Connectivity During Surgical Anesthesia.

Duan Li,Mike P Puglia,Phillip E Vlisides,Amy Mckinney,Ka I Ip,Mackenzie Zierau,Andrew P Lapointe

doi:10.3389/fnagi.2019.00371

Abstract

An advanced understanding of the neurophysiologic changes that occur with aging may help improve care for older, vulnerable surgical patients. The objective of this study was to determine age-related changes in cortical connectivity patterns during surgical anesthesia. This was a substudy analysis of a prospective, observational study characterizing cortical connectivity during surgical anesthesia in adult patients (n = 45) via whole-scalp (16-channel) electroencephalography. Functional connectivity was estimated using a weighted phase lag index (wPLI), which was classified into a discrete set of states through k-means analysis. Temporal dynamics were quantified by occurrence rate and state transition probabilities. The mean global connectivity state transition probability [13.4% (±8.1)] was not correlated with age (ρ = 0.100, p = 0.513). Increasing age was inversely correlated with prefrontal-frontal alpha-beta connectivity (ρ = −0.446, p = 0.002) and positively correlated with frontal-parietal theta connectivity (ρ = 0.414, p = 0.005). After adjusting for anesthetic-related confounders, prefrontal-frontal alpha-beta connectivity remained significantly associated with age (β = −0.625, 95% CI −0.99 to −0.26; p = 0.001), while frontal-parietal theta connectivity was no longer significant (β = 0.436, 95% CI −0.03 to 0.90; p = 0.066). Specific transition states were also examined. Between frontal-parietal connectivity states, transitioning from theta-alpha to theta-dominated connectivity positively correlated with age (ρ = 0.545, p = 0.001). Dynamic connectivity states during surgical anesthesia, particularly involving alpha and theta bandwidths, maybe an informative measure to assess neurophysiologic changes that occur with aging.

Highlights

Brain health is a growing concern among patients and perioperative physicians, with aging surgical populations
We tested the hypothesis that the global connectivity state transition probability during the stable maintenance phase of surgical anesthesia would decrease with advanced age
As the brain ages, the propensity to undergo transitions between brain states may become less likely during general anesthesia

Summary

Introduction

Brain health is a growing concern among patients and perioperative physicians, with aging surgical populations. Identifying cortical biomarkers that correlate with age may be scientifically informative and clinically useful for predicting a propensity for deleterious perioperative brain states. One proposed theory of cognitive aging views the senescence process as a metastable system that serves to preserve function but predicts impaired switching between network states (Naik et al, 2017). These concepts may be reflected by reduced connectivity state transition likelihood in older patients. As such, determining how perioperative connectivity patterns change with age, both globally and within certain bandwidths, might inform our understanding of neurocognitive function and vulnerability

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