A urinary tract infection may make memory problems worse after a traumatic brain injury, according to new research in mice.
The study raises an important question about whether a common infection could interfere with the brain’s recovery after an injury.
Traumatic brain injury, often shortened to TBI, happens when a blow, fall or other force damages the brain. Falls are a major cause, and people with moderate injuries can experience problems with memory, attention, sleep, mood and everyday tasks for weeks, months or longer.
Recovery does not happen only inside the brain. After TBI, changes can occur throughout the body, including in the immune system, and people recovering from brain injuries can be more vulnerable to infections.
Urinary tract infections, or UTIs, are one example. These infections usually happen when bacteria enter the urinary system, and E. coli is the most common cause of bladder infections.
UTIs are especially common in women and medically vulnerable people. Previous research has found that bladder infections also occur in people recovering from TBI and can contribute to hospital readmissions.
Scientists at The Ohio State University wanted to know whether a UTI could do more than create urinary symptoms after a brain injury. They asked whether the infection might also worsen problems with thinking and memory.
The researchers used female mice and divided them into groups. Some mice received a moderate brain injury under anesthesia, while others went through a similar procedure without receiving the actual brain injury.
Three days later, some animals were given E. coli bacteria in the urinary tract to produce a bladder infection. Other mice received a control treatment, allowing the researchers to compare the effects of brain injury, infection and the combination of both.
Six days after the brain injury, the animals completed tests that measured spatial memory. This type of memory helps an animal or person remember locations and understand where things are in the surrounding environment.
As expected, mice with a brain injury had poorer memory than animals without an injury. But when the brain injury was followed by a UTI, the memory problems became much worse.
The scientists then looked for changes that might explain this effect. They found altered signs of inflammation in several areas of the injured brain, suggesting that immune cells in the brain were reacting not only to the original injury but also to the infection in the bladder.
The researchers also found an unexpected change in the bladder. Brain injury by itself increased the presence of some immune cells there, even without a UTI.
That finding could be important because it suggests the relationship may work in both directions. A brain injury may change conditions in the bladder, while a bladder infection may send signals that influence an already injured brain.
The team also studied IL-6, a substance the immune system uses when responding to injury and infection. Changes in IL-6 in the blood provided further evidence that TBI may alter the way the whole body reacts when an infection occurs soon afterward.
Researchers do not yet know exactly how the brain and bladder communicate during this process. Nerves already connect the brain with the bladder to control urination, but immune signals may provide another pathway linking the two organs.
The research was led by Zachary Zimomra, Olga Kokiko-Cochran and colleagues at The Ohio State University, with collaborators from Washington University School of Medicine. It was published in the Journal of Neurotrauma in June 2026.
The study is important because UTIs are common and can sometimes be overlooked when a patient is already dealing with a major health problem. If bladder infections truly worsen thinking after TBI in people, identifying and treating them quickly could become an important part of brain injury care.
However, the findings need to be interpreted carefully. This was an animal study using female mice, the memory changes were measured only a few days after injury, and researchers cannot yet say that the same biological response occurs in humans.
The next step is to study the brain-bladder connection in greater detail and include both male and female animals. Human research will ultimately be needed to learn whether preventing or quickly treating UTIs improves recovery after TBI.
Overall, the study provides an intriguing warning that recovery from brain injury may be influenced by health problems elsewhere in the body. It does not prove that a UTI causes lasting cognitive decline in people, but it gives researchers a strong reason to investigate a common infection that may have been underestimated.
Source: The Ohio State University
