For the study, Dr. Naoki Saji and colleagues at the National Geriatrics and Gerontology Center in Obu, Aichi, Japan, analyzed stool samples from 128 older adults, with or without dementia.

In general, the researchers found that patients with dementia had higher concentrations of some compounds – including ammonia, indole, and phenol – but lower levels of Bacteroides.

Bacteroids are a group of bacteria that can be beneficial to the intestines because they eliminate the "bad" bacteria that cause the infection.

For now, said Fargo, the relationship between the gut microbiome and the disease is an interesting and "booming" area of ​​research. But it is unclear whether microbes have a direct effect on the risk of dementia.

Other recent studies have examined whether chronic infection was related to dementia. Last week again, researchers announced they have discovered the bacterium that causes gum disease in the brains of people with Alzheimer's disease.

In tests on mice, they showed that bacteria could move from the mouth to the brain, where they attacked nerve cells.

Other research has revealed particularly high levels of some herpes virus in the brain of people with Alzheimer's disease.

All this suggests that "external agencies" could play a role in dementia, according to Fargo. But, he said, nobody knows what's going on yet.

Sano accepted. She said that while the presence of some infectious bedbugs has been linked to dementia, it may not be the infections themselves that matter. The bacteria of gum disease and herpes viruses are extremely common, Sano said. So transporting these insects alone is not the critical factor.

Instead, Sano speculated, there might be something in the body's general response to "an insult or injury" that is the real problem.

Fargo recommended that people focus on lifestyle-related factors that are closely related to improving brain health: exercise regularly, do not smoke, and adopt a healthy diet. the heart.

He also stressed the importance of reducing blood pressure. An important trial published this week found that "intensive" blood pressure control – less than 120 mm Hg – reduced the risk of developing lighter memory and thinking problems in the elderly.