Could Humans Have a Brain Microbiome?

Bacteria thrive in almost every corner of the planet, from deep-sea hydrothermal vents to high up in the clouds.

Scientists have long assumed that bacteria can’t survive in the human brain.

A new study published in Science Advances provides the strongest evidence yet that a brain microbiome can and does exist in healthy vertebrates.

Scientists have long been skeptical that the brain could have a microbiome because all vertebrates, including fish, have a blood-brain barrier.

They found bacteria in the brains of healthy salmonids, including rainbow trout and Alaskan Chinook salmon, were home to living microbes.

The researchers even caught a bacterium in the act in the process of crossing the barrier.

Early hints that microbes exist in the olfactory bulbs of healthy mice and, to a lesser extent, throughout the brain.

If microbes have adapted to cross the fish blood-brain barrier and survive in the fish brain, they could do the same in our bodies.

Even in small numbers, Link said, resident microbes could influence our brain metabolism and immune systems.