Between 8% and 20% of the elderly who for some reason need to be hospitalized have episodes of delirium, an acute and generally reversible disorder of consciousness and cognition. In these cases, the individual becomes disoriented, with a disconnected speech and it is common that he does not recognize loved ones. This is a different picture from delirium – as hallucinations caused by mental illnesses are popularly known – and an important sign that the elderly's brain is suffering.
In search of biomarkers that help diagnose the problem and also therapeutic targets, researchers from the University of São Paulo ( USP ) analyzed the intestinal microbiota of 133 patients over 65 years of age hospitalized at the Hospital das Clínicas of the Faculty of Medicine of USP ( HC-FMUSP ). The research results were published in the scientific journal The Journals of Gerontology
“We identified that elderly people with a less diverse microbiota were more likely to develop delirium. And that the patients who actually developed the condition carried a greater amount of enterobacteria - microorganisms associated with pro-inflammatory pathways and the modulation of important neurotransmitters", explained the Dr. Flavia Garcez , first author of the article. The doctor collaborated with the research activities of the Geriatrics Service of HC-FMUSP and received, in 2019, the award NIDUS Junior Investigator Award , which provides funding for research on delirium.
The work with the elderly hospitalized at HC-FMUSP is part of a larger project, by the Research Support Foundation of the State of São Paulo ( FAPESP ), which investigates diagnostic and prognostic markers in critically ill patients treated at an emergency service.
“The gut microbiota has gained attention in recent years. It has been linked to several conditions such as obesity, insulin resistance and inflammatory bowel disease. Disturbances in the microbiota have also been linked to chronic neuropsychiatric illnesses such as depression and Alzheimer's disease. However, little was known about the relationship between microbiota and delirium, a disorder that, although very prevalent, is still fraught with mysteries,” said the , coordinator of the study supported by FAPESP.
brain-gut axis
According to Dr. Flávia Garcez, the association between microbiota and delirium was already expected and the work showed that this relationship is possibly bidirectional, with one influencing the other. “There is the gut-brain axis, connected by the vagus nerve that serves as a two-way communication between the gastrointestinal tract and the brain. Other than that, previous studies had already demonstrated the relationship between the microbiota and a sister disease of delirium, Alzheimer's,” said the researcher.
However, she pointed out, the work has advanced in understanding this relationship. “The interesting thing about this study is that we were able to evaluate the microbiota of the same individual repeatedly, before and after he had delirium. With this, we found that the set of microorganisms in the intestinal tract changed when the same patient went in and out of delirium,” she highlighted.
For the research, the researchers collected sociodemographic, clinical and laboratory data throughout the entire period of hospitalization. The intestinal microbiota was analyzed from samples obtained by swabs rectums (a kind of swab that is passed in the anus region) upon admission and 72 hours after patients are admitted to the hospital. A third sample was collected as soon as the volunteer had delirium. The group used the W Onfusion Assessment Method (CAM) to assess, twice a day, the presence of the disorder during hospitalization.
Candidates who, up to 24 hours before hospital admission, used probiotics, prebiotics or artificial nutrition, as well as those with acute gastrointestinal disorders, severe traumatic brain injury, history of recent hospitalization or institutionalization, were excluded from the analysis.
In addition to analyzing the microbiota, the group also investigated factors related to inflammation, such as the circulating level of cytokines – molecules that signal to the immune system the need to send more defense cells to the site of infection. However, no significant differences were found between patients who had or did not have delirium.
“O delirium é a alteração neuropsiquiátrica mais comum em pacientes internados e pode ser definido como o cérebro em sofrimento. Por isso é tão importante avançar na investigação e identificar marcadores. Quando se fala em insuficiência renal, existe o exame de sangue. Para insuficiência respiratória, é possível ver o paciente com falta de ar. Mas para uma insuficiência cerebral, como o delirium, ainda não existe um marcador definitivo”, explicou o Dr. Júlio César Garcia de Alencar , professor do curso de Medicina da Faculdade de Odontologia de Bauru ( FOB-USP ) e coautor do estudo.
Acesse o artigo científico completo (em inglês).
Acesse a notícia completa na página da Agência FAPESP
Fonte: Maria Fernanda Ziegler, Agência FAPESP. Imagem: Freepik.
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