Gut bacteria may contribute to delirium in elderly patients after surgery

Postoperative delirium—a sudden, fluctuating and typically reversible disturbance of mental status in patients that occurs after anesthetized surgery—is a common postoperative complication. The causes, progression and biological signatures are largely unknown, however.

Now researchers have conducted a first-of-its-kind study that shows an association between gut microbiota and postoperative delirium.

Early studies in elderly mice found that anesthesia/surgery induced an age-dependent changes in postoperative gut microbiota and postoperative behavior, including postoperative delirium-like behavior.

In their current work, a clinical observational study conducted between 2016 and 2020 at Mass General, a research team led by Yiying (Laura) Zhang, MD, Ph.D., collected fecal swabs from patients undergoing knee or hip replacement surgery or laminectomy under general or spinal anesthesia.

The team used 16S rRNA gene sequencing to assess gut microbiota then used a new method called Dimension-reduction Algorithm in Small Human-datasets (DASH) to analyze the relationship between gut microbiota and postoperative delirium.

The method combined statistical algorithms and domain expertise to filter through a large amount of data and accurately extract important signals.

In the 10% of patients who developed postoperative delirium, the researchers found that higher levels Parabacteroides distasonis—a bacterium associated with gut wall health that has a varying role in different diseases—was positively associated with postoperative delirium after adjusting for age and sex.

"DASH was especially helpful in a small dataset where data-driven methodology alone was not enough to find a connection between gut bacteria and postoperative delirium," says Zhang, the lead and corresponding author of the study.

It would appear the delirium seen in older persons after surgery could be from misbalanced gut bacteria, influenced by anesthesia. This was an association, however.

It could be possible these patients had a higher amount of Parabacteroides distasonis before the operation, or that something unknown was actually influencing it and this was just a fluke.

It might be safe to eat your probiotics or yogurts/kefirs and get adequate fiber, to minimize issues, just in case.

I’m probably not reading the text correctly.
The last sentence or two seems to say;

“Higher levels Parabacteroides distasonis- a bacteria associated with gut wall health - was positively associated with
postoperative delirium”.

It almost sounds like they are saying if you’re carrying what is thought to be a healthy amount of gut wall bacteria, then you are MORE LIKELY to experience postop delirium.

I want to understand the basics of this theory since I’m in a situation where I typically have one to three surgeries a year. Most minor, but still requiring anesthesia.

Obviously, the proper course of action is for the elderly to forego medical care and substitute it with an intake at the nearest Soylent Green facility. They do wonders with the elderly.

Nostalgia joke moment:

Q: Have you heard about America’s newest aircraft carrier, the USS Ronald Reagan?

A: It wanders the oceans aimlessly until someone brings it back to it’s home port.

Parabacteroides distasonis is the type strain for the genus Parabacteroides, a group of gram-negative anaerobic bacteria that commonly colonize the gastrointestinal tract of numerous species. First isolated in the 1930s from a clinical specimen as Bacteroides distasonis, the strain was re-classified to form the new genus Parabacteroides in 2006. Currently, the genus consists of 15 species.

Parabacteroides genus has been associated with reports of both beneficial and pathogenic effects in human health. Herein, we review the literature on the history, ecology, diseases, antimicrobial resistance, and genetics of this bacterium, illustrating the effects of P. distasonis on human and animal health.

Recently, we isolated and fully sequenced multi-drug resistant P. distasonis from deep-gut wall tissue lesions in patients with Crohn’s Disease that underwent surgical removal of the affected bowel further supporting a potential pathogenic role on gut wall health. Recent studies suggest that P. distasonis could exert protective effects against certain diseases, including multiple sclerosis, type II diabetes, colorectal cancer, and inflammatory bowel disease. Furthermore, some reports suggest that this bacterium could even have the potential to serve as a potential probiotic to promote digestive health in humans based on microbiome or animal studies. However, other experimental data show contradictory results, suggesting pathogenic effects in various disease models. This suggests that P. distasonis may serve a dichotomous role depending on the context, including the susceptibility of the host to immune suppression, impaired bacterial clearance, and the promotion of hyperinflammatory responses, together with strain-to-strain differences that may account for differences in antimicrobial resistance to human therapies and P. distasonis potential for pathogenicity.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8253142/

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