Older people who have delirium after surgery are at higher risk for cognitive decline. (iStock) (iStock/iStock)

Older patients who become disoriented or confused after surgery are more than three times more likely to develop dementia later, a new study has found.

The report, published Friday by the British Journal of Anaesthesia, assesses the effects of postoperative delirium (POD) on people 65 and older who were cognitively normal before their operations. Of 1,152 such patients, 9.5 percent met criteria for mild cognitive impairment or dementia a median of nine months after surgery.

The frequency of being diagnosed with MCI or dementia after surgery was much higher — 33.3 percent — among those who had experienced postoperative delirium, compared with 9 percent among those who had not.

While earlier studies have shown a relationship between POD and dementia, this is the first to look entirely at subjects who showed no cognitive decline in pre-surgery assessments, said David Warner, an anesthesiologist at Mayo Clinic in Rochester, Minn., and the study’s senior author.

Delirium is defined by an acute state of confusion, inattention, disorganized thinking and a fluctuating mental state. Older patients are more likely than younger ones to develop it after surgery, as are people with lower education levels and those who undergo vascular procedures.

Further study is needed to determine whether delirium contributes to later cognitive decline or is an indicator of some underlying factor that made people more likely to develop dementia, Warner said.

“Either it’s a marker,” he said, “or maybe there’s something about developing delirium that increases your risk for dementia. If it is the latter, then you really ought to do something” to reduce the incidence of delirium.

That could include using different techniques for anesthesia or postoperative pain management.

Most of the patients in the study underwent general anesthesia, and while there was no indication that this put them at higher risk, it could be worth studying whether using regional anesthesia techniques, such as spinal epidurals, reduced the incidence of delirium, Warner said.

Pain-control techniques could also be adjusted. “We’ve used opioids for pain control traditionally after surgery almost exclusively,” he said. “Now, partly because of the opioid epidemic, we are looking more at multimodal techniques.”

Adjustments to the postoperative environment could also reduce delirium. Earlier studies have recommended the use of clocks, calendars and similar materials to help reorient a patient after surgery. The presence of family members and minimization of staff changes and nighttime disruptions, and providing access to glasses and hearing aids can also help.

Older people are not the only ones who may suffer deleterious cognitive effects after surgery — studies have shown that exposing babies to general anesthesia may negatively affect their future cognitive development, Warner said.

“This is just another sign that we really need to pay attention to brain health at the time of surgery,” he said.