Post-Op Mood and Cognitive Changes: Undisclosed Effects

After surgery, it was as if the previous personality vanished. Why?

Posted Mar 20, 2019

A friend of mine was concerned about the mental state of his mother after she underwent major surgery. “She isn’t behaving like herself,” he said. “She won’t stop talking, even though she used to be very quiet. And she argues with her doctor, is irritable with the grandchildren when they come to visit, and refuses to eat. If I didn’t know better, I would think my mother was manic.“

After talking to the surgeon, my friend did "know better," because he was told that his mother was indeed manic, and if the mania did not go away in a couple of more weeks, she would be treated for this mental disorder. The cause? According to the surgeon, it was probably from the anesthesia.

She did get better, but her son remained upset over what happened. “No one told my mother or anyone in the family that people can develop mental and cognitive problems after surgery. She had to have the operation, but if someone had said something, we would have been prepared to deal with her behavior.”

Had he seen an article published in Scientific American in 2014, he would not have been surprised. In her review of the effects of anesthesia on the post-operative mental status of patients, Carina Storrs describes the growing awareness among surgeons that anesthesia may be responsible for post-operative delirium, confusion, hallucinations, depression, mania, and even psychotic behavior.

Post-operative mood and thought disorders have been noted among surgical patients, but it was assumed that surgery itself and its aftermath of pain, the discomfort of being in the hospital, and general stress were the cause. Over the past several years, however, attention has focused on anesthesia as more likely to be the risk factor for these mental disorders, including post-surgical psychosis and, more commonly, depression.

Not all anesthesia produces a vulnerability to these mental changes. The Scientific American article points out that there are different types of anesthesia, and usually only anesthesia that makes the patient unconscious is associated with mental and cognitive after-effects. Local anesthesia is the most frequently used, and most of us have had it for a filling or tooth extraction, for example. Its effect is mild; it is delivered to a small region and wears off quickly.

Regional anesthesia is often used for orthopedic procedures, is injected into the spine, and blocks nerve signals to the brain, thus blocking the perception of pain. A sedative drug such as propofol is usually given as well, but only enough to make the patient unaware of what is going on. Short-acting sedatives are often used for procedures such as colonoscopy; the patient is not unconscious but does not feel (or should not be feeling) any pain or anxiety during the procedure.

General anesthesia or deep anesthesia (which consists of a mixture of drugs) is used to make the patient unconscious. If the surgical procedure requires it, the patient can be unconscious for hours.

Delirium, or as it is sometimes termed, “mental fog," is a not-uncommon consequence of deep anesthesia and the elderly may be particularly susceptible. Researchers followed patients who had heart bypass or heart valve surgery, and who exhibited delirium post-operatively for a year after their surgery to see how long these cognitive changes persisted. They found that some patients who exhibited delirium continued to have cognitive deficits for as long as six months, and even a year after their operation.   

Nevertheless, it is important to remember that other factors may cause or exacerbate changes in mood and cognitive function after surgery. The effects of pain, anxiety, physical impairment, being in an intensive care unit, being alone, and countless other factors may influence emotional state after an operation. Even when the outcome is positive and the hospitalization brief, the physiological stress is sufficient to jolt the patient’s emotional stability.

But is the patient prepared for this? Is the family (or others) who are there to support the patient post-operatively prepared? How many of us facing elective surgery when there is time to talk to the surgeon and learn about the postoperative recovery are told that we may feel depressed, manic, delirious, and/or confused sometimes for days or weeks or months after the surgery? A friend told me that her three-year-old daughter was depressed after minor ear surgery. When the mother reported this to the surgeon, she was told that depression was common after the anesthesia used for that procedure. Why wasn’t the mother informed about this possibility ahead of time? Why wasn’t my friend told that his elderly mother was more susceptible to post-operative delirium and mood changes because of her age?

Technology, which shortens the duration of surgical procedures and thus time being anesthetized, should help reduce the possibility of mental and cognitive problems post-operatively. Shortening the length of hospitalization also may be helpful, as the patient can return to a familiar and undoubtably more comfortable environment. But the impact of the drugs used in anesthesia on brain function should not be discounted. Patients and their families certainly ought to be told to be prepared for some mental confusion or depression during recovery.


“The Hidden Dangers of Going Under,” Carina Storrs, Scientific American 2014  4, 34-35.

“Postsurgical psychosis: case report and review of literature,” Abdullah M, Al-Waili, Baban N et al, Adv Ther. 2006; 23:325-31

“Cognitive Trajectories after Postoperative Delirium,” Saczynski J , Marcantonio E, Lien Q et al,  N Engl J Med. 2012 367: 30–39.

“Changes in mental function after anesthesia and surgery,” Hansen M, Bigler D Ugeskr Laeger 1992; 154: 2000-3.

“Cognitive Trajectories after Postoperative Delirium,” Saczynski J , Marcantonio E, Lien Q et al,  N Engl J Med. 2012 367: 30–39.