People who have frequent or severe urinary tract infections may be at a greater risk of developing dementia, a study suggests.
As 7 million Americans live with dementia - a figure that's expected to double by 2050 - scientists are increasingly focusing on identifying preventable risk factors to stop the rise.
Obesity, diabetes, high blood pressure and environmental pollution have all been found to increase the risk in recent reports.
In fact, one recent study found half of dementia cases may be tied to modifiable lifestyle factors that form years before diagnosis.
Now, researchers in Finland believe severe urinary tract infections (UTIs) and other bacterial diseases are associated with a higher risk of developing dementia years, or even decades, later.
They noted severe bacterial infections such as UTIs, which affect 10 million Americans per year and over half of US women in their lifetime, raised the risk of dementia by 19 percent.
While the exact link is unclear, the team from the University of Helsinki suspect the inflammation triggered by bacterial infections puts the immune system into overdrive, which damages tissues and cells in the brain responsible for memory.
Researchers also believe UTIs that occur five to six years before a dementia diagnosis could accelerate the disease's progression.
UTIs could be associated with a 19 percent increased risk of developing dementia, a study suggests.
'This time frame suggests that the inflammatory insult resulting from infections severe enough to require hospital treatment may accelerate the pre-existing preclinical stage of dementia rather than initiate neurodegeneration in a cognitively healthy person,' the researchers wrote in the journal PLOS Medicine.
UTIs are caused by bacteria that infiltrates the urinary system from sexual activity, catheter use and changes to vaginal flora due to menopause. Women are also at a greater risk of UTIs because they have shorter urethras, allowing bacteria to reach the bladder faster.
Most patients experience a burning sensation when they urinate, a stronger or more frequent urge to urinate and dull or stabbing pain in the abdomen or back. In older adults, these infections can also cause an altered mental status, which can mask the signs of dementia.
The majority of UTIs clear up after several days of antibiotics, but left untreated, they can lead to kidney or bladder infections, blockages in the urethra or sepsis, the body's overreaction to an infection.
UTIs are also more common in older women as beneficial bacteria in the vagina decline and pH rises, making it easier for harmful bacteria to colonize. The vaginal and urethral tissues also become thinner and drier with age, allowing bacteria to enter the urinary tract.
Researchers in the new study looked at medical data from 62,555 people in Finland who had been diagnosed with late-onset dementia, meaning they were diagnosed at 65 or older. The average participant age was 81, and 60 percent of patients were women.
There were also 312,772 healthy controls who did not have dementia.
The study identified 29 risk factors for dementia, including heart disease, neurological diseases such as epilepsy and Parkinson's, mental health issues such as anxiety and endocrine disorders such as type 2 diabetes. Of the 29 disorders, two were infections: UTIs and unspecified bacterial infections.
There were several limitations to the study, including not having data on UTI treatments or investigating subtypes of dementia such as Alzheimer's disease or vascular dementia.
UTIs can be prevented by staying hydrated to flush bacteria out of the bladder, wiping from front to back after using the restroom, avoiding holding urine for long periods of time to prevent bacteria growth and wearing cotton or loose-fitting underwear.