Does Delirium Drive Cognitive Decline?
After surgery, half of older adults develop delirium, which may speed up the rate of cognitive decline.
Delirium is an abrupt, fluctuating change in cognitive abilities and awareness that is common among older adults who are hospitalized. Roughly half of older adults develop delirium within minutes or hours after surgery, increasing the risk of long-term health issues, cognitive decline and dementia.
Since many people develop delirium while hospitalized, researchers weren’t certain whether the cognitive decline is actually driven by hospitalization instead of delirium. The latest research published in JAMA Internal Medicine provides more proof that episodes of delirium, and not the hospital stay, drive future cognitive decline.
“We were surprised to learn that rehospitalizations did not explain any of the effect of delirium on cognitive decline,” senior study author Sharon Inouye, professor of medicine at Hebrew SeniorLife and director of the Aging Brain Center at the Hinda and Arthur Marcus Institute for Aging Research, said in a press release.
How does delirium occur?
Dr. Jason Karlawish, a neurologist and professor of medicine at the University of Pennsylvania, told Being Patient in a LiveTalk that delirium, “is a product of many different factors coming together.” The aging brain, acute illness, changing environments, medications, and other noxious stimuli lead to confusion. “It doesn’t have to be at a hospital, but there’s something about hospitalization that makes it even more likely to occur,” he added.
Some people become hyperactive and agitated, while others become withdrawn. In both cases, people with delirium aren’t able to pay attention to their surroundings like they used to. Delirium could also wax and wane, meaning that someone may be temporarily attentive before slipping back into an episode.
While it is a risk factor for cognitive decline and dementia, delirium is not mild cognitive impairment — a more prolonged state of cognitive and memory impairment.
Is delirium driving cognitive decline?
The researchers recruited 560 adults aged 70 or older who underwent major elective surgery. Each individual received cognitive testing at baseline and again after five years to investigate the relationship between delirium, hospitalization, and cognitive decline.
Almost one in four participants developed delirium after surgery. Those who developed delirium were also 42 percent more likely to experience rehospitalization due to falls or serious illness, and more likely to experience a faster rate of cognitive decline.
However, when the researchers took a closer look at the data, they found something surprising: The hospitalization didn’t seem to explain the link between delirium and cognitive decline. The finding contradicts the notion that delirium might be a marker of someone who is already less healthy and more likely to develop cognitive decline.
“It’s a very nicely done study,” Dr. Babar Khan, a pulmonary and critical care clinician and professor at the Indiana University Center for Aging Research at Regenstrief Institute, who wasn’t involved in the study, told Being Patient. “I’m a little surprised with the finding.” It suggests that after a rehospitalization, there is a temporary cognitive setback that the individual bounces back from. Delirium, on the other hand, has a permanent impact.
One major limitation, he mentioned, is that the researchers do not know if the individuals in the study developed delirium during rehospitalization.
Preventing Delirium
While there aren’t any effective treatments for delirium, an estimated 40 percent of delirium cases are preventable. Khan pointed out several strategies: ensuring an individual stays hydrated during their stay, access to their glasses and hearing aids, and ensuring opportunities for physical mobility during the stay.
Although prevention is simple, Khan said that “as humans we don’t do common sense things that commonly.” It also requires staffing more physical and occupation therapists at hospitals to prevent these episodes.
He said it’s important to advocate for loved ones when they go to the hospital for an elective surgical procedure, or due to an infection or fall, to reduce the risk of delirium.
FAQs
White episodes of delirium are temporary, they increase the risk of future cognitive decline and dementia. The acceleration in cognitive decline is linked to the delirium episode itself and not the hospitalization.
About 40% of delirium cases are preventable through simple, supportive care strategies including ensuring that a person remains hydrated, has access to their glasses and hearing aids to reduce confusion, and is encouraged to stay physically mobile while in the hospital.
Postoperative delirium is caused by a combination of factors, including critical illness or the physical stress of hospitalization, that temporarily overwhelm the brain. Other triggers that increase the risk include anesthesia, strong medications, dehydration, and disorientation in the hospital.
