How to use probiotics to prevent dementia

Certain types of bacteria have been shown to target the brain and improve cognitive function

Bacteria rule the world, and they always will. They are like a metaphor for life: some are good, while others are downright evil.

Once, we thought that they were all bad and had to be exterminated. The presence of vast colonies of bacteria in the gut was discovered in the late nineteenth century. So repulsed were many sensitive but affluent individuals by that discovery that they had their colons removed by the royal surgeon Sir William Arbuthnot Lane as treatment for what was termed ‘intestinal toxaemia.’

Fortunately, that was a short-lived craze. Today we know that trillions of bacteria thrive in and on us, and we’re ok with that.

Knowledge of how gut bacteria influence health has gone mainstream. The microbiota oversee not just digestion, but every bodily system.

And, it would appear, some of the good bacteria are responsible for maintaining memory and keeping your mental faculties sharp. The wrong sort will do the opposite, and hasten cognitive decline.

I write regularly about dietary strategies that are proven to promote and maintain brain function, and looking after your gut microbiota is no less important than any other approach.

This year kicked off with some really exciting research in the field of dementia prevention and the role of the microbiota. A systematic review of the literature published in January examined the effect of certain probiotics on the treatment of Alzheimer’s and other neurodegenerative diseases.

The results were positive. The conclusion was that certain types of gut bacteria can stave off and even reverse what many consider to be the inevitable, but which clearly isn’t.

Where it all begins

When things go wrong in the gut, and they often do, a state of ‘dysbiosis’ is created.

Just as humankind has managed to lay waste to the external environment, so too do we frequently trash our own internal environment. Dysbiosis is the opposite of symbiosis; it is dissonance instead of harmony.

Dysbiosis arises when overgrowth of pathogenic, or ‘bad’ bacteria and other hostile microorganisms leads to changes in metabolic activity, as these undesirables colonise the gut in greater than normal amounts and send the friendly bacteria into retreat.

The activity of these dysfunctional microorganisms results in the release of potentially toxic metabolites that are linked to many chronic conditions.

One of those conditions is dementia.

‘In this regard, the gut microbiota is crucial in maintaining human health by regulating metabolism and immune responses, and increasing evidence suggests that probiotics, particularly beneficial bacteria, can enhance memory and cognitive functions.’

Research into the microbiota and its role in health beyond the gut always circles back to the gut-brain axis, a bidirectional line of communication between the central nervous system and the digestive tract. It is ‘increasingly recognized as a critical factor in the neuroinflammation and neurodegeneration observed in AD’ (Alzheimer’s disease).

The vagus nerve is the primary route of the gut-brain axis. This is the longest nerve in the body and it serves as a superhighway between brain, gut, and internal organs. Signals from the gut microbiota are transmitted to the brain along this nerve.

The systematic review mentioned above revealed that friendly bacteria - probiotics -work by creating metabolites that reduce brain inflammation and oxidative stress. These metabolites are despatched to the brain along the gut-brain axis. Oxidative stress arises when free radical production surpasses the body’s stockpile of antioxidants available to neutralise them.

Know your friends

An awful lot of bacteria are indigenous to the human body. There are approximately 39 trillion in total, and around 130 different types, or genus. Bacteria are classified by their genus, and each genus has numerous sub-species.

Different bacteria appear to perform different roles. Some, it would appear, are tasked specifically with creating metabolites that favour brain function.