New research indicates that biological markers linked to gut bacteria can identify dementia risk before symptoms appear.

Scientists have identified subtle changes in the blood that may reveal the earliest signs of cognitive decline long before symptoms become obvious, according to research from the University of East Anglia (UEA). The study, published in the journal Gut Microbes, suggests that chemicals produced by gut bacteria could serve as biological warning signs for dementia.

“Early detection is critical because by the time dementia symptoms become obvious, much of the brain damage has already happened,” says David Vauzour, PhD, lead researcher from UEA’s Norwich Medical School, in a release. “Identifying biological warning signs earlier could allow for timely lifestyle changes, targeted interventions, and better monitoring.”

Analyzing the Gut-Brain Axis

The researchers analyzed blood and stool samples from 150 adults aged 50 and older. The cohort included healthy individuals, those with mild cognitive impairment (MCI), and individuals experiencing subjective memory lapses who perform normally on standard cognitive tests but report concerns regarding their memory.

Using sensitive laboratory techniques, the team measured 33 key molecules produced by gut microbes and diet. Participants also provided stool samples to map the unique communities of bacteria living in their digestive systems.

“Using advanced computer modelling and AI-powered machine learning, we explored whether specific combinations of these gut and diet derived chemicals could separate the healthy from those experiencing early cognitive decline,” says Vauzour in a release.

Machine-Learning Accuracy

The study found striking shifts in both gut bacteria and the metabolites released into the bloodstream, even in participants who had only recently noticed mild memory changes. A machine-learning model built on six of these metabolites was able to classify participants into the three study groups with 79% accuracy.

Additionally, the model distinguished healthy adults from those with MCI with more than 80% accuracy. The chemical changes in the blood were strongly linked to differences in specific gut bacteria, adding weight to the importance of the gut-brain axis—the communication network between the digestive system and the brain—in cognitive aging.

“While we’re not yet at the point of providing a diagnostic test, our work suggests we may be able to use dietary and microbial information to help catch the presence of dementia earlier in life, potentially even before significant brain damage has occurred,” says Dr Simon McArthur, co-author from Queen Mary University of London, in a release.

Future Prevention Strategies

The findings highlight the potential of the gut microbiome as a target for protecting brain health. Researchers suggest that if specific gut bacteria or the chemicals they produce contribute to early cognitive decline, future prevention strategies could include treatments involving diet, probiotics, microbiome-based therapies, or personalized nutrition.

“This study is exciting because it links advanced data analysis with a clinically realistic goal of finding a simple and acceptable way to detect risk earlier,” says Dr Saber Sami, Alzheimer’s Research UK UEA lead and co-author, in a release. “It could add to a new set of methods that help bridge the gap between discovery science and practical tools for prevention.”

The research was led by UEA in collaboration with Queen Mary University of London and was part-funded by Alzheimer’s Research UK.

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