How to Avoid Delirium After Surgery

Delirium during a hospital stay is surprisingly common, and it can accelerate long-term cognitive decline, especially in older adults

Marlene Cimons

Reviewed by

Jason Karlawish, M.D.

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Published April 20, 2026

An illustration of a man standing in a hospital with an IV pole as pieces of his head float away

Courtesy of Jackson Gibbs

Key takeaways

Postoperative delirium — a sudden, often temporary, state of confusion — can be more than a short-term complication; it may raise the odds of long-term cognitive problems.
Older adults and people with underlying brain vulnerability (including early or unrecognized dementia) appear to be at greatest risk.
Steps to reduce risk include reviewing medications, bringing eyeglasses/hearing aids to the hospital, promoting sleep and mobility and minimizing unnecessary sedatives.

Dr. Paul Schulz has seen it countless times: patients who come into his clinic with signs of dementia that first appeared or worsened after a hospital stay.

“One woman told me her husband hadn’t been the same since his hip replacement,” recalls Schulz, professor of neurology at the McGovern Medical School, UTHealth in Houston. “He had been fine before but was now suffering memory loss and couldn’t concentrate.”

It wasn’t the surgery itself that prompted the husband’s cognitive decline. More likely, it was the effects of an episode of delirium following the operation, Schulz says.

Delirium, a temporary state of confusion and disorientation, can afflict postsurgical patients as well as those who didn’t have surgery but are critically ill in intensive care. Delirium and dementia are not the same. “Dementia” is an umbrella term for conditions that impair a person’s ability to think, reason and remember at levels that interfere with daily life. But delirium can lead to dementia. It’s not inevitable, but the risk is real, especially in older adults, clinicians say.

In 2020, AARP’s Global Council on Brain Health (GCBH) released a report describing the dangers of delirium, including its link to dementia. Since then, research has further solidified the connection. This includes a March report in The Lancet adding evidence that older hospitalized people in relatively good health are also at very high risk of future dementia if they experience delirium.

Also, a study of older adults having hip surgery reported in 2025 finding a significantly faster decline in memory and thinking skills in people who were mentally sharp before hospitalization but experienced delirium compared with those who didn’t.

And a study reported in The BMJ in 2024 showed that delirium tripled the odds of later dementia in hospitalized patients over age 65. Each additional episode added about 20 percent more risk.

“Since 2020, the evidence has become much firmer,” says Alasdair MacLullich, professor of geriatric medicine at the University of Edinburgh, an author on the Lancet paper and a member of the GCBH panel that wrote the 2020 report. He and others say they would like to see delirium routinely included in public discussions about risk factors for dementia.

“This is a massive public health problem that is largely invisible to the public unless you have it, or a family member has it,” says Dr. E. Wesley Ely, professor of medicine and critical care at Vanderbilt University Medical Center, another author of the 2020 report. “This has to change if patients are to escape delirium’s potential long-term cognitive consequences.”

What are the risks, and who is vulnerable?

Patients with delirium can become confused and disoriented — some even experience hallucinations. “You’ll hear them say things like ‘Why are all those ants coming down the wall?’ Or ‘Why are there birds in the hospital room?’ ” Schulz says.

But scientists stress that delirium is usually temporary. Patients without preexisting cognitive risk factors can recover, especially if the episode is brief. “If your brain is OK, you should recover with no ill effects,” says Dr. Alex Bekker, professor and chair of the department of anesthesiology at Rutgers New Jersey Medical School. An estimated 6 million Americans older than 65 experience delirium every year, according to the 2020 report.

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Certain medical conditions can exacerbate delirium — infections, diabetes or heart failure, for example — causing the confusion to persist, Ely says. This significantly increases the risk of future cognitive problems, even in cognitively normal people, he says. A lengthy attack of delirium can harm even healthy brain cells.

“The longer it lasts, the bigger the problem and it’s less likely you can bounce back and recover. If you had a short episode of delirium — eight to 12 hours — you’re probably out of the woods,” Ely says. “But every additional day of delirium increases the risk of long-term cognitive impairment by about 35 percent.”

Several other studies have confirmed the delirium-dementia connection in older adults. And a bout of delirium can be especially bad for someone already experiencing cognitive decline.

A patient already diagnosed with dementia, even if it’s mild, can experience a dramatic spike in symptoms, Ely says.

A bout of delirium can also jump-start cognitive decline in those who are asymptomatic but predisposed to Alzheimer’s disease, Schulz says. “Plaque has been slowly building up in their brains over years before symptoms appear,” he says, referring to abnormal amounts of amyloid beta, a protein found clumped together in the brains of Alzheimer’s disease patients.

Delirium affects up to half of older surgical patients, with a 40 percent greater risk per year after surgery of developing cognitive decline compared with those who do not experience delirium, “making it vital for us to avoid delirium and, if it occurs, to follow [patients] over the next few years to detect cognitive decline as early as possible,” Schulz says.

Cardiac surgery patients appear to be at a greater risk than those having elective or minor procedures, according to several studies. In one review, postoperative cognitive impairment affected between 10 and 40 percent of patients in the weeks following their procedure. Fewer than half fully recovered within a year.

“If people wake up from anesthesia and are fine, they are less likely to develop dementia,” Schulz says. Postoperative delirium “changes the whole game.”

How to prevent delirium

First come the steps to take in advance of the hospital stay to help prevent delirium.

Aim to strengthen your physical and mental resilience at least a month in advance: Eat healthfully, including a high-protein diet, exercise regularly, get enough sleep and stop smoking and drinking alcohol. Bekker also suggests doing cognitive exercises. “The idea is to make you as strong as possible,” he says. “The healthier you go into surgery, the healthier you will come out.”

Review medications with your doctor to identify those that may increase risk of delirium. These include benzodiazepines, anticholinergic drugs, sedative sleep medications and unnecessary opioids, which all affect the brain. And consider having a cognitive screening, even if you’re experiencing no symptoms.

Bekker also recommends patients ask if they can receive lighter levels of anesthesia appropriate for their type of surgery, even discussing with their physician whether the surgery is necessary, he says.

In the hospital, sensory deprivation can cause delirium. It can happen when “a patient is stuck in a hospital bed without glasses or hearing aids, and their circadian rhythms get messed up,” Ely says. What to do? “Remove the drugs. Fix the environment. Get them out of bed and moving,” he says.

Patients entering the hospital should bring their glasses, hearing aids and a list of medications they are taking to reduce the risk.

Current research is aimed at identifying people at greatest risk for delirium-induced dementia. Ely is leading a study examining the brains of ICU patients after death, looking for common threads beyond what is already known, such as time spent on a ventilator, or other shared medical conditions.

“We may find something completely different we haven’t seen before,” says Dr. Julie Schneider, director of the Rush Alzheimer’s Disease Center at Rush University in Chicago, one of the study investigators with Ely.

For now, though, MacLullich and others would like to see delirium front and center among dementia risk factors.

“A dementia framework that counts diabetes and hearing loss but effectively sidelines acute [delirium] episodes is conceptually out of date,” he says. “Given the size and consistency of the delirium effect, I do not think the dementia world can go on treating it as peripheral.”

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Marlene Cimons is a Maryland-based writer who specializes in health, science and the environment.

Jason Karlawish, M.D., is a professor of medicine, medical ethics and health policy, and neurology at the University of Pennsylvania. He is codirector of the Penn Memory Center, where he treats patients, and author of The Problem of Alzheimer’s, and he writes the monthly column Neurotransmissions for STAT.

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