Taking a daily probiotic may help slow age-related cognitive decline

• Results from a clinical trial showed that people with mild cognitive impairment who were given a probiotic for 30 days scored higher on cognitive tests.
• After the trial, the gut microbiome of participants who took probiotics contained less of a type of bacteria associated with cognitive impairment.
• The findings suggest that manipulating gut bacteria could hold promise for addressing cognitive impairment and other chronic conditions.

A clinical trial suggests that treatment with a probiotic could help people with mild cognitive impairment (MCI) regain cognitive function.

With the worldwide surge of dementia and Alzheimer’s disease (AD), “there is an urgent need for more research,” said lead study author Mashael R. Aljumaah, a microbiology doctoral candidate at the University of North Carolina at Chapel Hill.

During the double-blind randomized trial, people with cognitive impairment received a daily probiotic — Lactobacillus rhamnosus GG — for three months, after which their scores on cognitive tests improved.

Analyzing participants’ stool samples, the researchers found substantial levels of Lactobacillus rhamnosus GG, or LGG, as well as a reduction in the amount of another family of bacteria, Prevotella, often observed in people with cognitive decline.

These changes suggest a beneficial shift in the composition of participants’ microbiome.

“LGG [bacteria] emerged as a potential therapeutic probiotic based on numerous previous animal studies, which demonstrated its positive effects on several physiological conditions. LGG is also known for its acid tolerance and its ability to adhere in the gut, which makes it an effective probiotic.”

– Mashael R. Aljumaah, lead study author

The research is being presented at the NUTRITION 2023 gathering in Boston, MA, this week. The clinical trial results were also published in the scientific journal Clinical Nutrition in 2022.

Effects of probiotics on mild cognitive impairment

For the study, researchers compared people with mild cognitive impairment to those without the condition.

They sought to observe, understand, and attempt to influence the early stages of cognitive decline. Part of that effort involved identifying biomarkers that may signify the beginnings of cognitive impairment.

Researchers enrolled 169 participants varying in age from 52 to 75 years old in the clinical trial. People without cognitive impairment were assigned to one group as a control, and those with cognitive issues were assigned to another group.

Both groups received either LGG or a placebo for three months. No adverse effects were observed in either group.

Aljumaah and her colleagues identified one such biomarker, Prevotella, in people with cognitive impairment. The fact that the receipt of LGG appeared to reduce its presence suggests the sort of microbiome re-balancing that may one day be possible.

“By designing microbiome-targeted interventions, we can potentially slow down the progression of cognitive impairment,” Aljumaah told Medical News Today.

Prevotella bacteria linked to chronic conditions

Aljumaah explained that despite its presence in people with cognitive decline, it is not entirely clear that the role of the Prevotella family of microbiota is entirely negative.

For instance, Prevotella bacteria has been associated with autoimmune and inflammatory disease and cognitive impairment. It is often found in people with rheumatoid arthritis (RA) or inflammatory bowel diseases, including Crohn’s disease, Aljumaah said.

In addition, Prevotella bacteria is associated with metabolites that are important for gut health, and, coming from plant-based foods, it may play a role in processing fiber.

“This raises the question, if some species or strains within the Prevotella genus might contribute to these conditions, or could a certain genetic trait or mechanism be responsible?” Aljumaah noted.

Larger studies with LGG bacteria needed

Dr. Santosh Kesari, a board certified neurologist and director of neuro-oncology at the Pacific Neuroscience Institute in Santa Monica, CA, who was not involved in the study, told MNT he found the delivery of cognitive benefits to participants “intriguing.”

Still, Dr. Kesari called for larger studies to confirm its findings and ensure that no toxicities result from introducing LGG bacteria.

In addition, he expressed concern that an effort to solve a problem by introducing a probiotic to the gut microbiome may unbalance its bacterial mix, causing adverse effects.

“Focusing on a positive effect on brain health could have a counterproductive effect in another organ system,” Dr. Kesari said.

How the gut-brain connection affects health

“It’s important to note that our comprehension of the specific mechanisms linking the gut microbiome to cognitive health is in its infancy,” Aljumaah said.

“More specifically, our knowledge about which members of the gut [microbiome] are involved remains limited,” said Aljumaah.

Aljumaah also proposed various pathways possibly connecting the two distant areas of the body, including the vagus nerve and the immune system.

There may also be metabolites such as short-chain fatty acids involved and even neurotransmitters produced in the gut microbiome.

Dr. Kesari suggested that the manner in which the microbiome can affect brain function may be more indirect.

“The microbiome has a significant effect on total body health, including brain function, because it’s really the gateway for nutrition, nutrients, and how things are metabolized,” Dr. Kesari said. “As the saying goes, you are what you eat, and this is really the scientific link to that.”

Altering the microbiome to improve health outcomes

The microbiome is arguably medicine’s most daunting and thrilling frontier regarding human health.

As the example of Prevotella demonstrates, the microbiome is also a complicated area of study.

Whether scientists will ever understand the microbiome enough to effectively and safely manipulate or re-balance its inhabitants, Dr. Kesari said, “I think it has to get there.”

“We certainly know that the major morbidities in the United States are related to nutrition and obesity, and a lot of stuff is avoidable, and part of that [involves] the microbiome. We’re certainly not going to be changing our eating habits any time soon. So, if we can get a probiotic that can help us stay healthier, I think that’s the only way to reduce the financial healthcare burdens.”

— Dr. Santosh Kesari, neurologist

Source: Read Full Article