People who are put under general anaesthesia may wind up with memory and cognitive deficits for days or weeks after surgery, scientists say.
In a new study, scientists gave mice a common anaesthetic, and found the drug caused memory impairments that lasted up to a week.
However, when they gave the mice another drug, after the anaesthetic, the memory effects were reversed.
The findings suggest that doctors should tell their patients that anaesthesia may affect their memory, said Dr Beverly Orser, a professor of anaesthesiology at the University of Toronto, in Canada.
"It's assumed that once the drugs are eliminated, our memories are going to go back to normal. But when we test patients before and after a surgical procedure, a large number exhibit deficits in memory performance," Orser told Live Science.
Orser and her colleagues set out to measure how one common anaesthetic affected memory in mice, as a model for humans.
In one experiment, the researchers gave mice a low dose of the common anaesthetic called etomidate, which works by binding to receptors on an animal's brain cells called GABAARs.
When the anaesthesia wore off, the researchers put the mice in an enclosure with two different objects, which the animals could explore. They then put the mice in an environment where one of the two objects was familiar, while the other was new.
If the mice remembered the familiar object, they would spend more time around the novel one.
After receiving the anaesthetic, the mice spent roughly equal time around the familiar and the novel objects, suggesting their memory of the object was impaired.
These memory deficits lasted up to a week, Orser said.
The researchers also found the memory effects appeared to be reversible. When they gave the mice a drug that blocked the receptors targeted by the anaesthetic, the animals performed as well in the novelty task as did animals that had not received any anaesthetic.
The study was published in The Journal of Clinical Investigation.
