Scientists from the United States have found an extremely unusual strain of E. coli in the bodies of elderly rats, which causes them to hallucinate and deprive them of the ability to remember new information, according to an article published in the journal eNeuro.
“With the onset of old age, our memory does not fade out gradually. It often happens that older people who have felt well recently, suddenly lose their ability to think clearly and fall into hallucinations after experiencing a serious illness. Even if this attack of delirium goes away, crises like this significantly increase the likelihood of developing dementia,”says Susan Patterson of Temple University in Philadelphia (USA).
The human body contains about 10 times more unicellular bacteria, fungi and other microflora than our own cells. Observations of recent years show that microflora can not only affect a person's metabolism and the likelihood of developing cancer and other diseases, but also his behavior.
For example, a year ago, American biologists discovered, experimenting on mice, that the development of autism may be associated with the absence of one type of microbes, the bacteria Lactobasillus reuteri, in the intestines of children and their mothers. In addition, Russian biologists have repeatedly suggested that microflora can influence more complex behavioral responses, affecting the level of hormones and signaling molecules of the nervous system.
Patterson and her colleagues uncovered another highly unusual example of the influence of microbes on the behavior and work of the brain of animals and people, studying how young and old rats reacted to various infections and recovered after recovery.
These experiments, the biologist notes, unexpectedly showed that infection of rats with certain strains of the common E. coli (Escherichia coli) led to extremely unusual consequences in cases where the animals were old enough.
As it turned out, the infection of two-year-old rats with these microbes led to the fact that the rodents became sharply stupid and lost their normal perception of reality. They lost the ability to memorize new information, including the position of the exit from the maze, stuck into walls for no apparent reason, and generally behaved inadequately.
By analyzing the chemical composition of their blood and various body tissues, scientists found that all these changes in brain and memory were generated by microbes that changed the way the immune system works.
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The ingress of bacteria into the rat's body, the researchers note, led to the fact that their immune cells began to produce huge amounts of signaling molecules, interleukins, that cause inflammation. When these molecules infiltrated the hippocampus, the memory center of rats, they disrupted the cells associated with long-term memories, leading to hallucinations and problems with mental acuity.
These abnormalities, according to biologists, disappeared only two weeks after the rats recovered. Most importantly, the functioning of the hippocampus in rodents has irreversibly changed, which may explain why severe infections often lead to the development of dementia and memory problems in the elderly. Accordingly, blocking interleukins can help protect older people from developing dementia and other impaired consciousness.
