Researchers have discovered a blood test that may identify individuals at an increased risk of cognitive decline, a condition often preceding dementia, well before conventional diagnoses are typically made. This breakthrough comes from scientists at the University of East Anglia (UEA), who have noted that subtle alterations in the blood might signal early signs of brain deterioration.

These blood changes are attributed to chemicals produced by gut bacteria. Dr. David Vauzour, leading the study at UEA’s Norwich Medical School, explained, “Significantly, the chemical variations found in the blood of participants were closely associated with specific gut bacteria. This finding supports the growing body of evidence that the gut-brain axis—the communication pathway between our digestive system and the brain—could be pivotal in cognitive aging.”

In this study, researchers examined blood and stool samples from 150 adults aged 50 and above. The group included both individuals with no cognitive issues and those with mild cognitive impairments.

Interestingly, some participants had normal scores on standard cognitive assessments but reported experiencing subjective memory lapses and a sense of unease about their mental state.

The blood samples were scrutinized to identify 33 essential proteins that originate from gut microbes or dietary sources. Additionally, the researchers analyzed stool samples to identify the unique gut bacteria communities present in the participants.

Dr. Vauzour noted, “By employing advanced computer modeling and AI-driven machine learning, we investigated whether specific combinations of these gut- and diet-derived chemicals could distinguish healthy individuals from those showing early signs of cognitive decline.”

“What we found was really striking. Even in people who had only just begun noticing mild memory changes, there were clear shifts in both their gut bacteria and the metabolites they release into the bloodstream.”

The team then built a machine-learning model which was able to distinguish healthy adults from those with mild cognitive impairment with over 80% accuracy.

Dr Vauzour added: “Dementia is one of the greatest public health challenges of our time. Identifying biological warning signs earlier could allow for timely lifestyle changes, targeted interventions, and better monitoring.”

Study co-author Dr Simon McArthur, from Queen Mary University of London, said: “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.

“We hope this work will pave the way for simple, non-invasive blood tests capable of identifying people at higher risk of memory decline years before dementia is typically diagnosed.”

The findings were published in the journal Gut Microbes.