Abstract
Background: Elderly patients with pre-existing cognitive impairment are susceptible to post-operative cognitive dysfunction (POCD). In this study, we investigated whether there is pre-existing local homogeneity and functional connectivity alteration in the brain before surgery for POCD patients as compared to that in non-POCD patients.Methods: Eighty elderly patients undergoing major thoracic or abdominal surgeries were recruited. Resting-state functional MRI was scanned at least 1 day before surgery. Neuropsychological tests (NPTs) were performed before surgery and at discharge, respectively. Pre-operative regional homogeneity (ReHo) and resting-state functional connectivity (RSFC) were compared between POCD patients and non-POCD patients, respectively. Partial correlation between NPTs and ReHo or RSFC was analyzed by adjusting for confounding factors.Results: Significant difference (P < 0.001, Gaussian Random Field (GRF) correction which is a multiple comparisons correction method at cluster level, cluster size > 49) in ReHo between POCD patients and non-POCD patients was detected in right hippocampus/parahippocampus. Pre-operative RSFC between right hippocampus/parahippocampus and right middle/inferior temporal gyrus increased in POCD patients (P < 0.001, GRF correction for multiple comparisons) when compared with that in non-POCD patients.RSFC significantly correlated with composite Z-score (r = 0.46, 95% CI [0.234, 0.767], P = 0.002) or Digit Symbol Substitution Test Z-scores (r = 0.31, 95% CI [0.068, 0.643], P = 0.046) after adjusting for confounding factors.Conclusions: The results suggest that premorbid alterations of spontaneous brain activity might exist in elderly patients who develop early POCD. The neural mechanism by which patients with pre-operative abnormal spontaneous activity are susceptible to POCD requires further study.
Highlights
The incidence of early post-operative cognitive dysfunction (POCD) is 25.8% in those who underwent major non-cardiac surgical procedures [1]
We aimed to explore the altered brain regions by using Regional Homogeneity (ReHo) analysis, and these brain regions were selected as regions of interest (ROI) for RSFC analysis
Thirteen patients were diagnosed with POCD, and the incidence of POCD was 26.7% at discharge
Summary
The incidence of early post-operative cognitive dysfunction (POCD) is 25.8% in those who underwent major non-cardiac surgical procedures [1]. There is accumulating evidence suggesting that pre-existing cognitive impairment (PreCI) is prevalent in geriatric elective surgical patients [2], and PreCI is likely a good predictor of cognitive dysfunction after surgery [3]. Patients with Alzheimer’s disease neuropathology (lower pre-operative cerebrospinal fluid Aβ1– 42) even in the absence of clinically detectable symptoms may be susceptible to POCD [4]. These findings indicate that pre-operative asymptomatic cognitive decline or neuropathology exists in patients who develop POCD. We investigated whether there is pre-existing local homogeneity and functional connectivity alteration in the brain before surgery for POCD patients as compared to that in non-POCD patients
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