Recent studies reveal that older adults hospitalized with severe infections face a significantly increased risk—up to three times higher—of developing fatal dementia in later years.

Researchers from the National University of Singapore have identified that hospitalizations due to critical illnesses such as sepsis, urinary tract infections, pneumonia, and necrotizing soft tissue infections elevate the likelihood of inflammation that can promote dementia. This issue is pertinent to as many as 33 million Americans.

Over a span of 25 years, the study highlights that vascular dementia presents a greater threat than Alzheimer’s disease. While Alzheimer’s predominantly impacts memory, vascular dementia often arises from strokes or reduced blood flow to the brain, leading to cell damage.

In the United States, approximately 2.7 million individuals are estimated to suffer from vascular dementia, compared to around 6.7 million affected by Alzheimer’s disease. The symptoms of these two dementia types can vary significantly. Vascular dementia is characterized by slow cognitive processing, attention difficulties, challenges in organizing thoughts or actions, and memory issues.

The study underscores that infections can compromise the brain’s protective barriers, allowing harmful pathogens to penetrate the central nervous system. This breach can cause widespread inflammation, which in turn results in brain damage.

The researchers found that infections can weaken the brain’s protective barrier, allowing dangerous pathogens to enter the central nervous system. This triggers widespread inflammation, leading to brain damage. 

Infectious pathogens may also cross the intestinal barrier, enter the blood and cross into the blood-brain barrier that way, causing low-grade chronic inflammation that kills off brain cells.

The heightened risk of dementia peaks shortly after an infection and can persist for years. Since long-term studies show that this link strengthens over time, early and ongoing cognitive screening for people hospitalized with these infections is crucial, especially for older patients after hospitalization.

The danger of dementia spikes right after a serious infection and remains high for years (stock)

The research team found that, overall, hospitalizations for a range of infections together raised the risk of later developing dementia by 83 percent.

People who were hospitalized for an infection were 60 percent more likely to develop Alzheimer’s disease and 268 percent, or 3.68 times as likely, to develop vascular dementia. 

Researchers determined this by analyzing 16 studies encompassing more than 4 million adults over 65 years old, including 1.2 million who had been hospitalized and 3 million who had not.

The standout finding was that sepsis, a life-threatening, body-wide response to infection, carries the highest risk.

Sepsis hospitalization was shown to increase the risk of any kind of dementia by about 80 percent over the course of almost two years to 25 years.

Sepsis, affecting roughly 1.7 million Americans every year, is a leading cause of death among seniors 60 and up, with a death rate hovering around 60 percent.

This was closely followed by pneumonia, responsible for about 10 million infections each year, which increases all-cause dementia risk by about 70 percent. 

Urinary tract infection (UTI) cases, which exceed eight million annually, or soft tissue skin infections that affect about 14.9 million Americans each year, raise dementia risk by 57 percent and 42 percent, respectively.

For adults over 60, sepsis is a leading cause of death, killing roughly 60 percent of patients

The study, published in the journal Aging, is the first to link hospital-treated infections with a higher risk of developing dementia.

It had some significant limitations, the researchers said.  

The first is that researchers could not measure the severity of infections or the length of hospital stays, nor how these specific measures influenced dementia risk. Most of the data they analyzed did not provide that information.

The body of research the team analyzed also varied drastically in their follow-up periods. 

While this prevented them from defining risk for specific short-term periods, it allowed them to spot an important pattern.

The studies that followed people for more extended periods consistently showed a stronger link between a severe infection and the eventual development of dementia.

With that, researchers urged doctors and nurses to be on high alert for seniors admitted to the hospital with rapidly progressing, severe infections, as early intervention ‘can potentially help to mitigate the risk of developing Alzheimer’s disease and Vascular Dementia.’