Perioperative neurocognitive and functional neuroimaging trajectories in older APOE4 carriers compared with non-carriers: secondary analysis of a prospective cohort study

Br J Anaesth. 2021 Dec;127(6):917-928. doi: 10.1016/j.bja.2021.08.012. Epub 2021 Sep 14.

Abstract

Background: Cognitive dysfunction after surgery is a major issue in older adults. Here, we determined the effect of APOE4 on perioperative neurocognitive function in older patients.

Methods: We enrolled 140 English-speaking patients ≥60 yr old scheduled for noncardiac surgery under general anaesthesia in an observational cohort study, of whom 52 underwent neuroimaging. We measured cognition; Aβ, tau, p-tau levels in CSF; and resting-state intrinsic functional connectivity in six Alzheimer's disease-risk regions before and 6 weeks after surgery.

Results: There were no significant APOE4-related differences in cognition or CSF biomarkers, except APOE4 carriers had lower CSF Aβ levels than non-carriers (preoperative median CSF Aβ [median absolute deviation], APOE4 305 pg ml-1 [65] vs 378 pg ml-1 [38], respectively; P=0.001). Controlling for age, APOE4 carriers had significantly greater preoperative functional connectivity than non-carriers between several brain regions implicated in Alzheimer's disease, including between the left posterior cingulate cortex and left angular gyrus (β [95% confidence interval, CI], 0.218 [0.137-0.230]; PFWE=0.016). APOE4 carriers, but not non-carriers, experienced significant connectivity decreases from before to 6 weeks after surgery between several brain regions including between the left posterior cingulate cortex and left angular gyrus (β [95% CI], -0.196 [-0.256 to -0.136]; PFWE=0.001). Most preoperative and postoperative functional connectivity differences did not change after controlling for preoperative CSF Aβ levels.

Conclusions: Postoperative change trajectories for cognition and CSF Aβ, tau or p-tau levels did not differ between community dwelling older APOE4 carriers and non-carriers. APOE4 carriers showed greater preoperative functional connectivity and greater postoperative decreases in functional connectivity in key Alzheimer's disease-risk regions, which occur via Aβ-independent mechanisms.

Keywords: APOE4; Alzheimer's disease; cerebrospinal fluid; functional MRI; intrinsic functional connectivity; neuroimaging; perioperative neurocognitive disorders; surgery.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Apolipoprotein E4 / blood*
  • Brain / diagnostic imaging
  • Cognitive Dysfunction / blood*
  • Cognitive Dysfunction / diagnostic imaging*
  • Cohort Studies
  • Female
  • Functional Neuroimaging / methods*
  • Geriatric Assessment / methods*
  • Humans
  • Male
  • Perioperative Care / methods*
  • Prospective Studies

Substances

  • Apolipoprotein E4