A blood test could help to identify people at higher risk of cognitive decline — often a precursor to dementia — years before a diagnosis is usually possible, according to researchers. Experts at the University of East Anglia (UEA) found that subtle changes in the blood may be an early sign of brain decline.
These changes were caused by chemicals produced by gut bacteria. Study leader Dr David Vauzour, from UEA’s Norwich Medical School, said: “Crucially, the chemical changes in the volunteers’ blood were strongly linked to differences in specific gut bacteria. This adds weight to growing evidence that the so‑called gut–brain axis — the communication network between our digestive system and the brain — may play an important role in cognitive ageing.”
The researchers analysed blood and stool samples from 150 adults aged 50 and over, including both healthy participants and those with mild cognitive impairment.
Some people in the study had also scored normally on standard cognitive tests but were experiencing subjective memory lapses and a feeling that something was not right.
The blood samples were analysed to measure 33 key proteins produced by gut microbes or from the diet. Researchers also looked at stool samples to map the unique communities of gut bacteria living in participants’ digestive systems.
Dr Vauzour said: “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.
“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.
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