Think Gut Health?

Why the gut matters in dementia research: highlights from our 2022 Research Conference

This week, we held our first hybrid Research Conference in Brighton! With nearly 500 delegates in person and other colleagues joining online, it was inspiring and uplifting to be back sharing the latest scientific updates. Our Early Careers Day on Monday was dedicated to early career researchers who presented their latest work and took part in careers-related sessions. This was followed by our main conference on Tuesday and Wednesday, exploring various topics and personal stories related to dementia.

One of the topics explored was how our gut influences risk of diseases that cause dementia. We already know that there are several steps we can take to help protect our brain health. Loving our heart, staying sharp and keeping connected form the basis of our Think Brain Health campaign, now in its second year.

But what about gut health?

Evidence suggests the gut can have far reaching effects on our body and health, and even affect processes in the brain.

In a session at our 2022 Conference, researchers shared their findings, explaining why we should perhaps also ‘think gut health’.

Gut bacteria, inflammation and new nerve cells

New research suggests that some gut bacteria in people with Alzheimer’s disease could slow the growth of new nerve cells in certain parts of the brain.

These findings were presented on Day 2 of our Research Conference. We were very fortunate to have two researchers explaining how gut bacteria affect inflammation and consequently the generation of new nerve cells in people with Alzheimer’s disease.

Gut bacteria are fantastic chemists. They produce a cocktail of molecules that can either increase or decrease inflammation. There is already evidence to suggest that people with Alzheimer’s disease have a slightly higher proportion of gut bacteria that increase inflammation than people without Alzheimer’s. However, whether this is a side-effect of the disease or whether it is something that starts the disease process is still unclear.

Prof Yvonne Nolan based at University College Cork is investigating how a person’s gut bacterial composition affects how new nerve cells form. Prof Nolan is interested in how this happens in a part of the brain called the hippocampus. The hippocampus is important for forming new memories, as well as emotions and spatial memory. For example, Prof Nolan explained that finding your car in a busy car park involves this part of the brain.

Prof Nolan’s team took stool samples (a good source of gut microbes) from people with Alzheimer’s disease and transferred the samples into rats. This resulted in the rats showing reduced rate of new nerve cell formation in their hippocampus. They also produced more chemicals that cause inflammation and performed worse in activities testing their hippocampus activity.

These findings prompted more questions: do gut bacteria cause Alzheimer’s symptoms? If so, can this effect be reversed by targeting the gut? While Prof Nolan’s research is in rats, not humans, it adds to existing evidence that points strongly towards bacteria as key players in neurodegenerative disease.

Dr Edina Silajdzic from King’s College London also studies nerve cell formation, gut bacteria and inflammation and has worked closely with Prof Nolan. Dr Silajdzic explained how she and Prof Nolan’s team analysed the types of gut bacteria in people with Alzheimer’s disease. The team took blood and stool samples from the participants to identify chemical signs of inflammation. Dr Silajdzic then took blood from participants with Alzheimer’s and measured how quickly new nerve cells formed with or without the blood. She found that giving the serum to nerve cells in a dish in the lab slowed new nerve cell formation.

These experiments are vital for understanding the mechanisms behind diseases like Alzheimer’s. Dr Silajdzic’s research paves the way for further testing to better understand how the gut microbes and inflammation affect brain health. This information is crucial in the search for new diagnostics, treatments and preventative measures for diseases like Alzheimer’s.

Tau tangles found in our ‘second brain’

Our gut quite literally has a mind of its own. An extensive network of nerve cells connects the gut with our brains, which is essential for digestion and vital communication between the two organs. This is known as the enteric nervous system (ENS), a kind of ‘second brain’.

We know that toxic protein clumps such as tau tangles form in brain cells in people with Alzheimer’s and frontotemporal dementia (FTD). This makes tau tangles a key target for developing new treatments to stop disease progression.

If tau tangles can form in brain cells, can they also form in the gut’s nerve cells?

Prof Pascal Derkinderen from the University of Nantes studies the types of tau found in our guts compared to tau found in our brains.  Prof Derkinderen explained how early evidence of tau in the gut and strong links between the gut and Parkinson’s disease has sparked more recent investigations into the gut’s role other brain diseases. Prof Derkinderen’s team have been studying chemical changes to tau in Parkinson’s and Progressive supranuclear palsy (PSP).

The team’s findings prompted several important questions. Do people with Alzheimer’s experience gut disorders? How could tau in the gut serve as a marker for dementia? Prof Derkinderen’s team will continue their research in this area to help find the answers. For now though, they have provided strong evidence showing that our ‘second brain’ in the gut is a valuable target for dementia research.

The journey continues…

Gut health is just one fascinating area of dementia research, where increasing evidence is bringing us closer to finding new interventions in the future. Other researchers at the conference presented posters also exploring the role of gut bacteria, and inflammation in diseases behind dementia.

It was very encouraging to see so many researchers investigating these systems coming together to share their discoveries. The findings presented here will pave the way for further investigations linking multiple aspects of neurodegenerative disease, from biomarkers in the gut to how diet and gut bacterial species can serve as potential targets for future treatments.