Now that scientists can easily determine the composition of a gut microbiome by sequencing the DNA in a stool sample, more and more associations are being found between the microorganisms in the gastrointestinal tract and human health. Dysfunction in the microbiome seems to lead to some diseases, and it may one day become more common to treat disease by using gut microbes or microbiome transplants. Fecal microbiome transplants (FMT) from healthy human donors have already been used to to successfully treat recurrent Clostridium difficile infections.
Researchers have now found that may be possible to use the microbiome to reverse some of the loss of brain and cognitive functions that typically accompanies aging. This work, which used a mouse model to demonstrate that some aspects of aging can be reversed with FMT, has been reported in Nature.
In this research, the authors showed that when gut microbes were transplanted from young mice into older ones, some aspects of brain and immune function were rejuvenated in the older mice. Not only did the elderly mice show behavioral changes that indicated a reversal of their aging symptoms, there was also evidence that after the FMT, the metabolism and gene expression in the hippocampus of aged mice were made more similar to what's seen in young mice.
The gut microbiome is thought to have a direct link to the brain through the gut-brain axis; there are nerves that go directly from the brain to the gut. More recently, researchers have begun to study the microbiota-gut-brain axis, in which the microbiome's influence on the endocrine system is also considered along with the central and enteric nervous systems.
Some previous research has found connections between the gut microbiome and aging; it seems to have a key role in the aging process, said Professor John F. Cryan of the APC Microbiome Ireland, part of the University College Cork.
As the number of older adults continues to increase worldwide and people are living to older ages, it will be important to ensure that medicine keeps up with these individuals. The study authors suggested that the microbiome could be one way to not only treat but reverse cognitive trouble.
"This new research is a potential game changer, as we have established that the microbiome can be harnessed to reverse age-related brain deterioration," said Cryan, who added that the mouse model also demonstrated evidence of improved learning and cognitive abilities.
Cryan acknowledged that there is a lot more work that has to be done before these findings can be confirmed in humans or used as a therapy. However, the microbiome represents an interesting therapeutic opportunity, because it might be possible to alter or maintain the composition of the microbiome with stuff like special foods or probiotics, and not drugs that may have many side effects.