A groundbreaking blood test may soon allow doctors to identify individuals at a heightened risk of developing dementia long before any symptoms emerge, according to recent research findings. Experts suggest this advancement could revolutionize the methods used to detect and manage the condition.

This innovative approach focuses on analyzing specific chemicals associated with gut bacteria and dietary habits. By doing so, it offers the potential to significantly alter the timeline for diagnosis and intervention, providing a crucial window of opportunity for those at risk.

When it comes to dementia, early detection is crucial. It broadens the spectrum of available treatments and grants patients the chance to adopt lifestyle changes that could safeguard their brain health and potentially delay the disease’s progression.

A team of researchers from the University of East Anglia conducted a study involving 150 participants, all aged 50 and older. These individuals were divided into three distinct groups: a healthy control group with no signs of cognitive decline, a group with Subjective Cognitive Impairment (SCI) who reported issues with memory and thinking yet showed normal test results, and a group with Mild Cognitive Impairment (MCI), which involves measurable early-stage cognitive decline and is a known precursor to dementia.

The participants provided both blood and stool samples for analysis. Using advanced laboratory techniques, researchers examined these samples for metabolites—chemicals produced by gut bacteria and influenced by dietary intake. This analysis could pave the way for earlier and more effective interventions in the fight against dementia.

The cohort gave blood and stool samples which were analysed using highly sensitive lab techniques to scan for chemicals produced by gut bacteria and diet, known as metabolites. 

Then, using advanced computer modelling and AI, the researchers looked for patterns in metabolites to see if they revealed early signs of cognitive decline.

They found clear changes in both gut bacteria and the chemicals they release into the bloodstream in those in the MCI group who had just begun noticing mild memory problems.

A blood test could identify people at higher risk of dementia years before symptoms appear

Everyone experiences dementia differently. Use this checklist to help you make a note of your symptoms before you talk to your GP.

A model based on just six chemicals was able to classify participants into the three groups with 79 per cent accuracy. It could distinguish healthy adults from those with mild cognitive impairment with over 80 per cent accuracy.

Dr David Vauzour, lead researcher from UEA’s Norwich Medical School, said: ‘Early detection is critical because by the time symptoms appear, much of the brain damage has already happened.

‘Identifying biological warning signs earlier could allow for timely lifestyle changes, targeted interventions, and better monitoring.’   

Around 982,000 people are currently living with dementia in the UK, a number expected to rise to 1.4 million by 2040. 

Globally, over 55 million people are affected, and this figure could reach 139 million by 2050.

The research, published in the journal Gut Microbes, also highlights the potential of the gut microbiome as a target for protecting brain health. Further research could identify certain supplements – such as probiotics – which could bolster people against the disease. 

Dr Vauzour added: ‘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 gut-brain axis – the communication network between our digestive system and the brain – may play an important role in cognitive ageing.

‘If particular gut bacteria or the chemicals they produce contribute to early cognitive decline, treatments involving diet, probiotics, microbiome-based therapies, or personalised nutrition could one day form part of dementia prevention strategies.’    

The new research was led by the University of East Anglia in collaboration with Queen Mary University of London. It was part-funded by Alzheimer’s Research UK.

Professor Fiona Carragher, Chief Policy and Research Officer at Alzheimer’s Society, said: ‘Blood tests could transform how we diagnose dementia and even identify a person’s risk of developing dementia in the future. Studies like this are helping to build a clearer picture of the early biological changes linked to the condition.

‘This is a small study looking at associations at a single point in time, so we cannot say whether these changes cause cognitive decline or are a result of it or whether these individuals went on to develop dementia. It does, however, add to a growing field of research looking at the connection between gut and brain health.

‘Understanding risk earlier could be key to helping people access support, take steps to reduce their risk, and take part in research. Alzheimer’s Society part funded the influential Lancet Commission on dementia prevention, intervention and care, which identified 14 modifiable risk factors for dementia and showed that up to 45 per cent of dementia globally may be preventable. 

‘Dementia is one of the biggest challenges facing our health and care system, and with the number of people affected set to rise to 1.4 million by 2020, prevention must be a central part of how we tackle it.’

Finding ways to stop dementia from taking hold is being treated as a global health emergency, with thousands of researchers exploring potential causes and early warning signs.  

In February, Swedish researchers isolated 17 factors that have the largest influence on two of the most common forms of dementia, Alzheimer’s disease and vascular dementia.

While some are predetermined or unchangeable, including age, genetics and sex, others, such as alcohol consumption, physical activity and smoking, are under a person’s control.

The team from Lund University in Sweden identified 17 fixed and flexible factors: heart disease, high cholesterol, heart medications, stroke status, age, blood pressure, smoking status, diabetes, low and high alcohol consumption, sleep, carrying the APOE e4 gene, depression, living alone, BMI, sex and education.