Charles L Raison, MD: How Gut Microbiota Can Affect Mental Health

Charles L Raison, MD:

Psychiatry is right on the edge of this astounding realization, that human beings are not just human beings, they're actually communities. We are a combination of our sort of mammalian selves and this huge world of bacteria, viruses and fungi that inhabit our guts, and are on our skin.

The realization that there's this huge amount of crosstalk between these other organisms inside us and our bodies and our brains. That crosstalk is hugely relevant for health.

We now know across a whole bunch of disorders that the function and composition, especially of the bugs in the gut powerfully affect illness. If you get sick, it changes the microbiota, but we now know that the changing of the microbiota - the changing of the composition of this bacterial world actually can set you up for illnesses.

It's really of course in the GI space - in the gastrointestinal space that this was first really clear, but it's increasingly clear that there are huge connections between the gut and the brain - we've known that for years and now we're realizing this huge connection between these trillions of microorganisms in the gut and the brain, and that in fact increasingly it looks like they're functioning can change how we think, feel and act.

Of course, that's interesting. There's now data - for instance depressed people have different composition of the microbiota in general than do non-depressed. Autistic people, schizophrenic people too. But of course, as clinicians, what we understand is the question of whether or not any of this has to do with treatment. Can we harness these scientific discoveries to improve people's mental functioning?

We're really at the beginning of this. But certainly in animal studies it's quite clear that if you change the microbiota, you change the behavior of the animal. There are just now a couple of studies suggesting that if you change the microbiota of humans, you can also impact their behavior.

There's evidence now that probiotics can be helpful for depression, and there's emerging data that a more radical treatment called fecal matter transplant - where you actually transplant fecal matter from a healthy person to an ill person, that it might really show promise in things like autism - that literally changing how the bugs in the gut work can change our emotional and cognitive selves.