High rate of certain bacteria in gut linked to better memory

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Researchers have found a strong connection between the amount of specific bacteria in the gut and the development of dementia.

As patients’ dietary habits and lifestyles affect bacteria in the body, the discovery could lead to the development of measures to reduce risk of the disease, they said.

The findings by Naoki Saji, deputy director of the Center for Comprehensive Care and Research on Memory Disorders of the National Center for Geriatrics and Gerontology, and his colleagues have been published in the British scientific journal Scientific Reports.

While more than 1,000 types of bacteria, weighing 1 kilogram in total, exist in the human intestines, their composition changes depending on the ages of the individuals.

The researchers, targeting those who visited the memory disorder center over a one-year period from March 2016, surveyed the rates of bacteria in the intestines and whether the patients had developed dementia by checking feces, MRI and psychological tests.

Analysis of valid data on 128 individuals in their 60s to 80s showed that when an indigenous bacterium called Bacteroides accounts for 30 percent or more of all bacteria, the patients have one-10th the risk of dementia compared with those with higher rates of other types of bacteria.

Bacteroides is known to exist in large numbers in thin people.

With regard to how bacteria in the intestines cause patients to develop dementia, substances produced by gut bacteria may cause cerebral inflammation, resulting in cognitive impairment, according to the scientists.

“We will follow up the surveyed patients to examine the association (between bacteria and dementia),” said Saji. “I also want to ascertain relations between bacteria and dietary habits so diet-based preventive measures (against dementia) can be developed.”

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