GFAP and delirium: In POD patients, the intraoperative increases in both plasma NfL [non-delirium vs. POD: −0.03 (−0.13–0.06) vs. 0.07 (0.01–0.29), P < 0.001] and GFAP [non-delirium vs. POD: 0.01 (−0.16–0.09) vs. 0.10 (−0.01–0.28), P = 0.008] were significantly higher than in non-delirium patients (Figures 3C, D).