People 60 and older who undergo elective surgery may be at higher risk of lasting memory problems, U.S. researchers said on Wednesday.

They said people 60 and older who have major surgeries such as joint replacements or hysterectomies are more likely to have cognitive problems after surgery.

And those who do are more likely to die in the first year after their surgery.

"We have known that patients undergoing heart surgery are at risk for cognitive dysfunction -- problems with memory, concentration, processing of information -- but the effects of non-cardiac surgeries on brain function are not as well-understood," said Dr. Terri Monk, an anesthesiologist at Duke University Medical Center, whose study appears in the journal Anesthesiology.

Monk led a team that examined hospital discharge records of 1,064 patients aged 18 and older who underwent testing for memory and cognitive function before surgery, at the time of discharge from the hospital and three months later.

They were put into three age groups: young (18-39), middle-aged (40-59) and elderly (60 and older). The groups were all of similar size.

Three months after surgery, cognitive deficits occurred in 12.7 percent of elderly patients, compared with just 5.7 percent of those in the young group or 5.6 percent in the middle-aged group.

The study suggests that overall, some 30 to 41 percent of adult patients undergoing major non-cardiac surgery have some form of memory or processing problem when they are discharged, but most people recover after three months.

But those 60 and older were more than twice as likely to still have problems three months after surgery. And those that had problems were more likely to die within the first year after surgery.

It is not clear why some patients suffer these problems, but it may be that surgery and anesthesia cause swelling in the brain that can affect the patient's ability to learn, retain or remember information, Monk said in a statement.

She said the study suggests the elderly may be predisposed to cognitive problems after major surgery. And knowing this might help doctors devise better strategies to prevent the effects of surgery and anesthesia on the aging brain.

(Reporting by Julie Steenhuysen, editing by Todd Eastham)