UTIs and other types of infections are closely associated with delirium, a short-lived state of confusion. About 30 percent of older people with UTIs develop delirium, and infections account for about half of delirium cases.
“I’m not sure that patients, the general public, know how UTIs can cause this,” said Shouri Lahiri, associate professor of neurology, biomedical sciences and neurosurgery at Cedars-Sinai Medical Center. “If they have episodes of confusion, it is an opportunity to seek medical advice, evaluate a possible underlying UTI. And by doing so, you will not only preserve short-term cognition, but perhaps even long-term cognitive function.”
How delirium can contribute to dementia
Delirium is a mental state of acute confusion and its distinctive features (inattention, executive dysfunction, and short-term memory impairment) fluctuate in severity. Delirium triggers include infections, as well as certain medical procedures and medications.
Delirium is usually thought of as a temporary cognitive state, but if its cause remains “unresolved or untreated, delirium can accelerate and become increasingly severe,” Lahiri said. “It can leave a permanent mark.”
It is also surprisingly common, especially among hospitalized patients. Some studies estimate that 15 to 30 percent of hospitalized patients and up to 70 percent of critically ill patients develop delirium. Annually, More than 2.6 million Americans over age 65 develop delirium.
Some people mistakenly think that delirium is normal in an older person.
“People think delirium is safe,” said Wes Ely, professor of medicine and co-director of the Center for Critical Illness, Brain Dysfunction and Survivorship at Vanderbilt University Medical Center. “It is very, very dangerous. “It is absolutely precarious for someone to go into delirium.”
In the short term, “delirium increases the length of hospital stay and is associated with increased mortality,” Lahiri said. “It is associated with unimaginable human suffering.”
Older adults are more susceptible to delirium because they likely have age-related changes in their blood-brain barrier and less “brain reserve” to compensate for additional challenges to their brain.
But delirium also has long-term costs if not managed properly.
“It’s something that accelerates chronic brain dysfunction,” Lahiri said. “I think it is a modifiable risk factor for Alzheimer’s disease and related dementias, because by mitigating it, you can reduce the progression of these diseases.”
Research has shown that people who were diagnosed with dementia and later developed delirium had twice the rate of cognitive decline compared to those who did not. There is also a dose-response effect of delirium on long-term cognition: the more severe the delirium, the greater the risk of dementia.
Infections increase risk of dementia
There is growing evidence that infections, including urinary tract infections, are themselves associated with an increased risk of dementia. A 2021 study tracked the electronic medical records of 989,800 adults aged 65 and older with no history of dementia or cognitive impairment in the United Kingdom.
After controlling for a wide range of other factors such as sex, ethnicity, smoking and alcohol consumption, the researchers found that overall, people who had any infection had a 1.53 times greater risk of developing dementia in compared to people without infection.
The more severe the infection, such as sepsis and pneumonia, the greater the chance of developing dementia later. People who were hospitalized had it worse, with nearly double the risk of dementia. But even milder infections, including urinary tract infections, increased the risk of later dementia 1.73 times.
The study was associative, so it cannot prove causality. People with dementia are also more likely to develop infections, for example. But the risk remained elevated even up to nine or more years after infection.
“What is really needed now is to really understand the mechanisms behind this association between infections and dementia,” said Rutendo Muzambi, a researcher at the London School of Hygiene and Tropical Medicine and an author of the study. Clinical trials are also needed to examine whether strategies to reduce infections reduce the risk of dementia, he said. saying.
A common factor may be inflammation caused by an immune response to the infection, first in the body, which can then spread to the brain.
The brain’s frontal lobes, which are important for executive function, and the hippocampus, which is crucial for memory, are particularly affected in delirium, said Ely, who co-authored a 2020 review on delirium.
In a 2021 study, Lahiri and colleagues reported that mice with UTI behaved like delirium: They were more anxious in mazes compared to mice without UTI. These behavioral changes were correlated with an increase in inflammatory cytokines and neuronal changes in the frontal cortex and hippocampus of the mice.
“Those cells are damaged and don’t behave well, so the patient can become confused,” Ely said. “And if that process continues and those cells die, that’s when you get dementia.”
How to reduce the risk of urinary tract infections, delirium and dementia
Stay hydrated and urinate frequently to reduce the risk of urinary tract infections. Watch if urinating becomes painful, difficult, or frequent, or if you start to have fever, chills, or fatigue.
Seek medical treatment immediately when you experience a UTI. This will reduce the risk of known serious complications, including delirium and sepsis, although more evidence is needed on whether this would also prevent the risk of dementia, Muzambi said.
For caregivers, keep your loved ones with delirium reoriented. Keep them mobilized and make sure they sleep well at night and are awake during the day, said Ely, author of “Every Deep-Drawn Breath,” a book on intensive care and delirium.
Address other common but preventable risk factors for dementia, such as hearing loss, excessive alcohol consumption, and smoking.
Do you have a question about human behavior or neuroscience? Email BrainMatters@washpost.com and we may answer it in a future column.
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