Research is continually showing that feeding our gut in the right way is crucial for improving and even preventing cognitive decline as we age – find out how to protect your brain.
Our Gut-Axis
The complex bidirectional interaction that occurs between gut and brain, called the gut-brain axis (GBA)² has changed many ways of thinking. Among these, is the relation between what we eat and the effects on our body.
Previously, the general belief was that the food we ate was responsible for releasing compounds more or less beneficial for our body or brain health.
Now, it seems that the food we introduce is responsible for feeding the bacteria in the gut. The substances released from the microbiome are responsible for our health.
This idea has had a very big impact, especially within the scope of mental disorders. What if a microbiome-friendly diet can prevent or even stop the occurrence of certain diseases?
Cognitive Science
The workings of our brain revolve around our ability to acquire knowledge, use information and reason. These functions all combine into what we call “cognitive function,” and describes our memory, attention and decision-making abilities³.
As we age, cognitive function declines. In some people, the deterioration is very soft, whereas for others it is more aggressive and leads to cognitive impairment – resulting in struggles with learning and remembering.
Cognitive decline affects many. The median global prevalence of cognitive impairment is estimated to be 19%. In media, 56.5 people every 1000 people are diagnosed yearly with cognitive impairment7.
Despite a big interest in the GBA, only a few interventions have analysed the link between cognitive impairment and gut microbiota in the elderly. Almost all the information we have so far come from animal studies. That’s what makes this study so significant.
Investigating The Gut-Brain Axis
Looking at people aged between 48 and 60 years old, researchers used six different tests in order to evaluate the cognitive performance of participants6.
Turns out, people with greater microbial diversity performed better in 5 out of the 6 cognitive tests.
Those with higher microbial abundance and number of species also had better scores in one of the tests.
Akkermansia, Branesiella and Lachnospiraceae FCS020 group were positively associated with the improvement of some of the cognitive tests
More specifically, Akkermansia, Branesiella and Lachnospiraceae FCS020 group were positively associated with the improvement of some of the cognitive tests, whereas Sutterella was negatively associated with the outcome of one test6. Also, Verrucomicrobia and Proteobacteria phyla were positively associated with the score of one test.
This study does not come without limitations. However, the findings are consistent with previous interventions performed on animals. They concluded that short-chain fatty acids (SCFAs) seem to play a pivotal role when talking about the brain.
Short-chain fatty acids (SCFAs) seem to play a pivotal role when talking about the brain.
SCFAs are metabolites produced in the large intestine thanks to the bacterial fermentation of dietary fibres and resistant starches. There is growing evidence that they play a very important role in the regulation of the central nervous system both directly and indirectly8.
In animal models, butyrate, one of the SCFAs, had a protective effect against vascular dementia, cognitive impairment and metabolic risk factors for cognitive decline and dementia.
In line with this study, former animal investigations found that the genus Lachnospiraceae appeared to be beneficial for the brain. Akkermansia is also positively associated with cognitive function and negatively associated with inflammation and adverse metabolic outcomes6.
Probiotics Reduce Stress
This research complements previous findings. Another study demonstrated elderly people who took probiotics with Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI for 12 weeks showed several improvements4.
Taking probiotics decreased the relative abundance of Eubacterium, Allisonella, Clostridiales, and Prevotellaceae – microbes linked with inflammation.
Taking probiotics decreased the relative abundance of microbes linked with inflammation.
In addition to this, the study shows that after 12 weeks of treatment, people receiving probiotics have better mental flexibility and were less stressed compared to the group that did not receive probiotics.
Changing Your Gut
Yes, your gut microbiome is modifiable. In fact, it’s estimated that almost 60% of the variation in the gut microbiome can be attributable to diet5.
Even if it has not been confirmed, the beneficial effects of the diet might come from the presence of nutrients such as omega-3, polyphenols, fibres and vitamins1.
This intervention is one of the few evidences that links the association between gut microbiota and cognitive impairment in humans. More studies like this are fundamental to acquire more specific and precise knowledge on the topic.
Unfortunately, these interventions are difficult to carry out and also have many factors that can influence the outcome.
However, the findings of Meyer and colleagues pave the way for prevention and treatment of cognitive impairment in later age. In this scenario, a healthy and balanced diet during life might be the key for a healthy brain.
Summary
- Recently, a lot of attention has been directed in the understanding of the link between the gut and brain.
- With age, cognitive functions start to decline in a more or less aggressive way.
- It seems that all together, a greater diversity, a higher number and a more even abundance of bacteria in the microbiota are responsible for a better cognitive performance.
- Gut microbiome interventions in the elderly with probiotics can improve their cognitive performance.
- Dietary intervention can be the key to prevent the burden of cognitive impairment associated with ageing.
- However, many factors can influence the cognitive development of each person; furthermore, studies performed in humans are still scarce due to the challenges they bring.
