Table 1:

Summary of Evidence and Future Directions

Summary	Questions for Future Research
Sleep
Chronic sleep disorders including obstructive sleep apnea are associated with future delirium	Can improving preoperative sleep quality reduce delirium risk? Can increasing perioperative adherence to Continuous Positive Airway Pressure (CPAP) prevent delirium?
Perioperative sleep disruption is a precipitating factor for delirium	Can restoring circadian rhythm, either naturally or with the use of melatonin, prevent delirium? Can preferential use of dexmedetomidine prevent postoperative delirium in patients requiring postoperative sedation?
Pain
Preoperative pain is a risk factor for postoperative delirium	Can optimization of preoperative pain lower the risk of postoperative delirium?
Poorly treated postoperative pain can precipitate postoperative delirium	Do multisource tools for pain assessment identify patients at risk for delirium? Does the use of multimodal analgesia prevent postoperative delirium?
Little evidence exists describing the association between postoperative pain and longer term PNDs	Is poorly controlled pain associated with delayed neurocognitive recovery? Does chronic postoperative pain increase the risk of postoperative neurocognitive disorder?
Cognition
Poor preoperative cognitive function is one the of the strongest predictors of PNDs	Which cognitive screening test(s) best predict PNDs? Does preoperative cognitive trajectory predict PNDs?
Perioperative cognitive exercise may prevent postoperative delirium	Can cognitive prehabilitation prevent PNDs? Which type of cognitive exercise is best suited to prevent PNDs? What is the most effective dose?