Currently submitted to: Journal of Medical Internet Research
Date Submitted: Oct 18, 2026
Open Peer Review Period: Oct 20, 2026 - Dec 15, 2026
(currently open for review)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Preoperative mixed reality comprehensive cognitive training reduces the incidence of postoperative delirium in older adults undergoing orthopedic surgery: a randomized controlled trial
ABSTRACT
Background:
Older surgical patients are frequently affected by postoperative delirium (POD), a complication with serious short- and long-term consequences. Although cognitive prehabilitation holds promise for prevention, its conventional delivery formats suffer from low engagement and poor adherence.
Objective:
We sought to determine whether preoperative mixed reality comprehensive cognitive training (MRCC) lowers the incidence of POD in older adults undergoing orthopedic surgery.
Methods:
In this prospective randomized controlled trial with blinded outcome assessment, 144 patients aged ≥65 years scheduled for elective orthopedic surgery under general anesthesia were allocated in a 1:1 ratio to receive MRCC—delivered through mixed reality (MR) glasses in 20-minute daily sessions on the 2 consecutive days before surgery (n=72)—or standard perioperative care (n=72). The primary outcome, the incidence of POD within 7 days after surgery or until hospital discharge (whichever came first), was assessed with the Confusion Assessment Method (CAM). Secondary outcomes comprised delirium characteristics, perioperative electroencephalography (EEG) biomarkers, postoperative pain trajectories, preoperative sleep quality, postoperative cognitive performance (paper-based and MR-based), recovery quality, and patient satisfaction.
Results:
POD occurred in 27 of 144 patients (18.8% overall): 6 of 72 (8.3%) receiving MRCC versus 21 of 72 (29.2%) under standard care, an absolute risk reduction of 20.9% (IRR 0.286, 95% CI 0.123-0.666; P=.004). Among the patients in whom delirium developed, episodes lasted a median of 1 day with MRCC versus 2 days in controls (P=.048). MRCC further improved preoperative sleep quality, attenuated movement-evoked pain, and enhanced postoperative recovery (all P<.001). EEG analyses revealed attenuated pathological delta slowing and preserved complexity of brain signaling.
Conclusions:
Brief preoperative MRCC significantly lowered the occurrence and duration of POD in older orthopedic patients and was accompanied by improvements in pain, sleep, and neurophysiological function. MR-based cognitive prehabilitation therefore emerges as a promising nonpharmacological option for preventing delirium in this population. Clinical Trial: Chinese Clinical Trial Registry ChiCTR2400093319; https://www.chictr.org.cn/showproj.html?proj=252634
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