What is postoperative delirium and is it associated with dementia risk?

Postoperative delirium (POD) is a sudden state of confusion and altered awareness following surgery that can manifest immediately after recovery from anesthesia and up to five days post-surgery. While the incidence of POD depends on many factors such as age, medical history, and type of surgery, POD affects up to 50% of older people undergoing surgery and two thirds of patients in the intensive care unit [1; 2]. POD itself is often temporary, lasting only hours to days; however, it is linked to long-term negative health effects, including lasting impacts on cognitive health. 

WHAT THE EVIDENCE SAYS

Delirium is a sudden and short-term change in mental status and distinct from dementia, a chronic condition associated with progressive decline in cognitive function. However, there is a bidirectional relationship between POD and dementia. Experiencing POD significantly increases one’s risk of dementia [3; 4] and cognitive decline [5]. The flipside is also true—people with poor baseline cognitive function have a significantly higher risk of developing POD [6; 7], and delirium often leads to faster progression of dementia [2].

There are several known risk factors for POD, including age over 65, male, poor baseline cognitive function, dementia, anxiety, depression, cardiovascular disease (history of stroke, ischemic attacks, atrial fibrillation, and others), high blood pressure, alcohol abuse, and sleep deprivation [1]. Some types and characteristics of surgery have also been associated with a higher risk of POD, including hip surgery, cardiac surgery, vascular surgery, emergency surgery, long surgical duration, and requirement of blood transfusion.

What causes POD? The answer is not straightforward because it involves multiple factors and is not caused by a single mechanism. Although general anesthesia used to be considered the major cause of POD in the past, recent clinical studies have reported that the use of regional anesthesia (e.g., nerve blocks or spinal blocks that avoid unconsciousness) does not lower the risk of POD compared to general anesthesia in older people undergoing hip fracture surgery [8]. More than the type of anesthesia, the physical trauma caused by the surgery itself increases inflammation in the body, which in turn disrupts the blood-brain barrier?, leading to the inflammation spilling over to the brain. Brain inflammation, called neuroinflammation, is considered to be one of the main drivers of POD, which explains why older people and people with dementia who tend to have higher neuroinflammation are at a higher risk of POD [9; 10]. Other mechanisms contributing to POD include surgery-induced neural network dysfunction, damage to neurons, and circadian rhythm disturbances.

WHAT YOU CAN DO TO PREVENT POD

Based on the delirium prevention consensus report published by the Global Council on Brain Health, up to 40% of delirium cases can be prevented [2]. The doctors and healthcare providers do their part to minimize risk, such as properly managing pain, orienting the patient to their surroundings, getting patients up and moving as soon as possible, and monitoring optimal hydration and nutrition. It is worth highlighting that there are many things that patients can do themselves to lower their risk of POD:

• Prepare for the surgery by building your physical and mental resilience with a healthy diet, plenty of physical activity, and adequate sleep.
• Inform your doctor if you have previously experienced delirium.
• Inform your doctor of all of the medications and dietary supplements you are taking.
• Bring your prescription glasses, hearing aids, and dentures if you use them.
• Ask friends and family to stay with you in shifts for the entire time you are in the hospital.
• Bring some familiar comforting objects from home, such as a favorite photograph, book, or music you like.
• Try to establish a normal routine by sleeping, eating healthy foods, and drinking water as soon as possible after surgery.
• Get exposure to sunlight during the day.
• Use an eye mask and/or earplugs to help you sleep better.
• Get moving as soon as possible after surgery and don’t hesitate to ask for help from staff.

 

1. Janjua MS, Spurling BC, Arthur ME (2026) Postoperative Delirium. StatPearls.
2. GCBH (2020) Preserving Your Brain Health During Illness or Surgery: GCBH Recommendations to Prevent and Treat Delirium
3. Lee SJ, Jung SH, Lee SU et al. (2020) Postoperative delirium after hip surgery is a potential risk factor for incident dementia: A systematic review and meta-analysis of prospective studies. Archives of gerontology and geriatrics 87, 103977.
4. Mohanty S, Gillio A, Lindroth H et al. (2022) Major Surgery and Long Term Cognitive Outcomes: The Effect of Postoperative Delirium on Dementia in the Year Following Discharge. The Journal of surgical research 270, 327-334.
5. Kunicki ZJ, Ngo LH, Marcantonio ER et al. (2023) Six-Year Cognitive Trajectory in Older Adults Following Major Surgery and Delirium. JAMA internal medicine 183, 442-450.
6. Marcantonio ER, Goldman L, Mangione CM et al. (1994) A clinical prediction rule for delirium after elective noncardiac surgery. Jama 271, 134-139.
7. Sadeghirad B, Dodsworth BT, Schmutz Gelsomino N et al. (2023) Perioperative Factors Associated With Postoperative Delirium in Patients Undergoing Noncardiac Surgery: An Individual Patient Data Meta-Analysis. JAMA network open 6, e2337239.
8. Fan G, Zhong M, Su W et al. (2024) Effect of different anesthetic modalities on postoperative delirium in elderly hip fractures: A meta-analysis. Medicine 103, e38418.
9. Ding XY, Zhang MH, Liu J et al. (2026) Recent advances in postoperative delirium in elderly patients: pathophysiological mechanisms, risk prediction, and therapeutic strategies. Frontiers in neuroscience 20, 1759910.
10. Li T, Lu Z, Qin T et al. (2025) Pathomechanism of postoperative delirium: Systemic inflammatory response and neuroinflammation following anesthesia/surgery. Neuroscience 581, 40-49.

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