Ask the Doctors: Immune system, age make a difference in UTI symptoms

Dear Doctors: A friend who is 74 had an episode recently where she suddenly sounded as though she had dementia. Her physician diagnosed it as an effect of a UTI. Can you talk about how UTIs in older people can mimic dementia? Why do they affect more women than men?

Dear Reader: A urinary tract infection, or UTI, can happen when any part of the urinary system comes into contact with bacteria. This includes the bladder, the kidneys and the ducts that carry urine.

In younger people, a UTI typically makes itself known with symptoms that include a burning sensation while urinating, a frequent urge to go that produces very little output, pressure or pain in the abdomen, and urine that appears dark or cloudy and may smell odd.

In older adults, however, these physical symptoms don’t always appear. Instead, one of the signs that an older adult has developed a UTI can be the altered mental state and cognitive lapses that you observed in your friend. This presents a danger because a urinary tract infection that goes untreated can lead to serious problems, such as kidney damage or even sepsis. These so-called “silent” UTIs can present a grave threat to the health of older adults.

UTIs tend to be more common in women than in men. This is due in part because the urethra, which carries urine from the bladder and out of the body, is shorter in women than in men. It’s also located closer to the rectum, a potential source of bacteria.

When it comes to the difference in symptoms between younger and older adults, the immune system is believed to play a role. As we age, our immune systems become less responsive. That means an infection can reach a more advanced state before the immune system responds and the symptoms of a UTI appear.

For some older adults with a UTI, the first symptom they notice is pain or an ache in the lower back. Unfortunately, that’s a sign the infection has reached the kidneys. However, a UTI isn’t the first thing that most people think of when they begin to experience pain or discomfort in the lower back.

The reasons are not yet completely clear as to why UTIs can lead to an altered mental status in older adults. One school of thought is that the surge in inflammation that accompanies an infection may adversely affect the behavior of certain neurotransmitters, thus interfering with brain function. When an older adult suddenly exhibits altered mental status, a urinalysis can check for the presence of certain compounds in the urine that suggest a UTI. A urine culture will pinpoint the specific bacterial culprit.

The good news is that antibiotics are an effective cure. Once patients with an infection complete their course of antibiotics, it’s a good idea to get a follow-up urine culture a few days later. It will let them know whether or not the UTI has completely cleared up.

Dr. Eve Glazier and Dr. Elizabeth Ko are internists at UCLA Health.