They are the key to stopping dementia may lie in the gut rather than the brain, new research shows.
Decades of research from around the world, costing billions of pounds, have so far failed to find a way to deal with the disease that robs memory.
But the gut “is an alternative target that may be easier to respond to with medication or dietary changes,” experts said.
A series of experiments linking the gut to the development of Alzheimer’s will be presented today at a medical conference.
One will reveal how microbiomes – the community of bacteria in the gut – of patients with the disease can differ significantly from those without the disease.
Another found that rodents that received fecal transplants directly from Alzheimer’s patients performed worse on memory tests.
A third study showed that brain stem cells treated with blood from patients with the disease were less able to grow new nerve cells.
In theory, patients’ intestinal bacteria affect the levels of inflammation in the body, which then affects the brain through the blood supply.
Inflammation is considered a key factor in the development of Alzheimer’s disease.
The disease is the most common type of dementia and one of the leading causes of death in the United Kingdom.
Charities estimate that approximately 900,000 people in the UK and 5 million in the US live with the disorder, a number that is growing every year as we live longer.
UK researchers present results of two experiments potentially linking gut microbiome to brain
Alzheimer’s disease is thought to be caused by plaque buildup in the brain, which ultimately causes brain cell death.
There is no ongoing treatment, but medications are already coming out to help reduce symptoms by helping nerve cells communicate.
Hopefully, treatments can be developed that target the gut, which can then improve the condition of the brain.
Dr Edina Silajdzic, a neurologist at King’s College London who analyzed samples from Alzheimer’s patients, said: “Most people are surprised that their gut bacteria can have an effect on their brain health.
“But the evidence is growing – and we’re building an understanding of how that happens.
“Our intestinal bacteria can affect the level of inflammation in our bodies, and we know that inflammation is a key factor in Alzheimer’s disease.”
WHAT IS ALZHEIMER?
Alzheimer’s disease is a progressive, degenerative disease of the brain in which the accumulation of abnormal proteins causes nerve cells to die.
This disrupts the transmitters that carry messages and causes the brain to contract.
More than 5 million people suffer from the disease in the United States, where it is the 6th leading cause of death, and more than 1 million Britons have it.
WHAT’S HAPPENING?
As brain cells die, the functions they provide are lost.
This includes memory, orientation and the ability to think and reason.
The development of the disease is slow and gradual.
On average, patients live five to seven years after diagnosis, but some can live ten to 15 years.
EARLY SYMPTOMS:
- Short-term memory loss
- Disorientation
- Behavioral changes
- Mood swings
- Difficulty working with money or making a phone call
LATE SYMPTOMS:
- Severe memory loss, forgetting close family members, familiar objects or places
- Become anxious and frustrated by the inability to make sense of the world, which leads to aggressive behavior
- Eventually he loses his ability to walk
- There may be eating problems
- The majority will eventually need 24-hour care
Source: Alzheimer’s Association
She is behind King’s study, which compares the microbiomes of 68 people with Alzheimer’s disease and a similar number who do not.
Blood and stool samples were taken from all participants and analyzed in a biological laboratory in Italy.
These tests revealed that people with Alzheimer’s disease have a different microbiome, as well as more markers of inflammation.
Subsequent experiments involving the treatment of brain stem cells with blood from people with Alzheimer’s disease.
They have been found to be less able to grow new nerve cells than controls treated with blood from people without the disease.
Dr Silajdzic said: “This leads us to believe that inflammation related to intestinal bacteria can affect the brain through the blood.”
Her team’s research will be presented at Alzheimer’s Research UK 2022 in Brighton today.
Another study that will be revealed looks at the effects of Alzheimer’s microbiome on rats.
Stool samples were taken from people with and without Alzheimer’s and then transplanted into the intestines of rodents.
Professor Yvonne Nolan, a neuroscientist at King’s who analyzed the results, said there were key differences in how the rats performed in the memory tests, depending on which sample they received.
“We found that rats with intestinal bacteria from people with Alzheimer’s disease performed worse on memory tests,” she said.
They also did not develop as many new nerve cells in memory-related areas of the brain and had higher levels of inflammation.
She added that this result suggests that Alzheimer’s disease, at least in part, could be caused by abnormalities in the gastrointestinal tract.
Previous studies have suggested that intestinal bacteria may be involved in a variety of brain functions, from appetite control to mental health conditions such as depression and anxiety.
Professor Nolan said that unlike the brain, the gut could be an alternative and easier part of the body to target potential Alzheimer’s treatments.
“Although it is currently difficult to deal directly with Alzheimer’s processes in the brain, the gut is potentially an alternative target that may be easier to respond to with medication or dietary changes,” she said.
Both sets of studies were not reviewed before the conference.
In response to new research, Alzheimer’s Research Director Dr Susan Koolhaas said they provided a good basis for further work on the link between intestinal bacteria and Alzheimer’s disease.
“Taking these results together reveals differences in the composition of intestinal bacteria between people with and without dementia and suggests that the microbiome may lead to changes associated with Alzheimer’s disease,” she said.
“Future research will need to build on these findings so that we can understand how gut health fits into the broader picture of genetic and lifestyle factors that affect a person’s risk of dementia.”
She added that in the meantime, people should actively try to keep their brains healthy with age to reduce the risk of developing Alzheimer’s.
“Current data shows that we need to stay in shape, eat a balanced diet, maintain a healthy weight, not smoke, drink only within recommended limits and keep blood pressure and cholesterol under control,” she said.