How urinary tract infections can trigger delirium and worsen dementia

Urinary tract infection induces host IL-6 response. IL-6 complexes with the soluble IL-6 receptor in the periphery and initiates IL-6 trans-signaling via the glycoprotein 130 transmembrane (gp130) receptor on neurons, resulting in neuroinflammation and neuronal apoptosis. Antimicrobial therapy attenuates IL-6 trans-signaling via mitigation of urinary tract infection, preventing subsequent brain injury. Credit: Alzheimer’s & Dementia (2026). DOI: 10.1002/alz.71184

Although urinary tract infections (UTIs) are typically minor—albeit painful—health issues for most people, they can pose serious risks for older adults, particularly those with Alzheimer’s disease and other forms of dementia. In older patients, a common UTI can trigger delirium, a medical emergency marked by sudden confusion and altered awareness. This condition can not only accelerate cognitive decline but is often mistaken for an underlying neurological condition—delaying proper diagnosis and treatment.

In a recent review published in the journal Alzheimer’s & Dementia, Cedars-Sinai researchers explored how UTI-induced delirium affects brain function, why individuals with dementia are especially vulnerable, and the critical need for early recognition and intervention.

“It’s a vicious cycle where dementia increases the risk of infection, and infection-related delirium accelerates cognitive decline,” said Shouri Lahiri, MD, principal investigator of the Critical Care Neurodegenerative Medicine Lab, director of the Neurosciences Critical Care Unit and Neurocritical Care Research at Cedars-Sinai, and senior author of the review.

Previous laboratory studies by Lahiri and his colleagues revealed that the immune system’s response to UTI-induced delirium—specifically the inflammatory protein interleukin-6—can cause changes in the brain. Blocking this pathway reversed delirium-like symptoms in mice.

Lahiri sat down with the Cedars-Sinai Newsroom to discuss UTIs as a potentially preventable and treatable contributor to cognitive decline and the importance of early recognition and swift treatment.

What is delirium, and how is it different from memory loss?

Delirium is a sudden change in thinking and awareness. It affects attention, judgment and short-term memory, and develops over hours or days.

Memory loss from conditions such as Alzheimer’s disease progresses slowly over time. Delirium, by contrast, is acute and usually triggered by a medical illness, such as a urinary tract infection, dehydration or infection elsewhere in the body.

Why can urinary tract infections cause confusion, especially in older adults?

Our research shows UTIs can cause acute brain dysfunction through inflammation. An infection in the bladder releases inflammatory signals into the bloodstream, which can affect the brain and disrupt normal function, leading to delirium.

Older adults are more vulnerable because their brains are often less resilient to physiological stress.

UTIs aren’t the only infections that can trigger this response. Any systemic infection, including pneumonia, gastrointestinal infections or skin infections, can provoke widespread inflammation that affects the brain and causes acute confusion.

Why are people with Alzheimer’s disease at higher risk for UTIs?

People with Alzheimer’s may have challenges upkeeping with hygiene and age-related hormonal changes that increase UTI risk. Alzheimer’s can also impair sensation and communication, making it harder for patients to recognize or report well-known UTI symptoms such as burning or urgency to urinate. As a result, infections may go untreated until they trigger delirium.

For people without dementia, delirium increases the risk of developing dementia by about threefold. Repeated episodes further raise that risk.

Why can a UTI make Alzheimer’s symptoms suddenly worse?

A UTI can cause a rapid cognitive decline that looks like a sudden worsening of Alzheimer’s disease. The key difference is timing. Alzheimer’s progresses gradually, while delirium causes an abrupt change from a person’s baseline.

We believe inflammation related to infection places added stress on an already vulnerable brain, which can worsen dementia symptoms and, in some cases, cause lasting damage.

Is delirium from a UTI reversible?

Early treatment offers the best chance for recovery. When UTIs are identified and quickly treated, delirium symptoms can improve or resolve. However, in some cases, cognitive effects can persist or become permanent. That’s why early recognition is critical.

Because UTIs don’t always cause obvious urinary symptoms, especially in older adults, we need to change the way we diagnose UTIs, using a mix of clinical observations and urinary and blood tests that show infection, to recognize when a UTI is behind sudden confusion.

How can caregivers tell the difference between Alzheimer’s progression and a UTI?

Sudden change is the biggest warning sign. Dementia generally does not cause abrupt declines. If someone with Alzheimer’s suddenly becomes much more confused, less alert or behaves very differently, that may signal delirium.

Other changes to look out for include changes in urination patterns, incontinence, pain, or changes in urine color or odor.

What can caregivers do to help prevent UTIs and delirium?

Caregivers should make sure the person they’re taking care of maintains good hygiene and adequate hydration. Caregivers should also notify a physician if UTIs are recurrent, because treatments are available to reduce repeated episodes.

Also, being aware of sudden changes in mental status and seeking prompt medical care can make a significant difference.

Are UTIs linked to delirium in other neurological conditions?

Yes. Parkinson’s disease is a key example. Many people with Parkinson’s have difficulty fully emptying their bladder, which increases infection risk. UTIs can worsen Parkinson’s movement symptoms, just as they worsen cognition in Alzheimer’s disease.

What is your lab studying next?

We are studying new drugs that target inflammatory pathways involved in UTI-related brain dysfunction, with the goal of advancing them to clinical trials. We are also developing diagnostic approaches to better identify UTIs in patients who don’t have the well-known urinary symptoms.

Antibiotics reduce UTI-related delirium in preclinical study