Most people, however strongly they might hold to what they regard as a scientific view of life — that we are biological organisms, products of evolution, not destined for a supernatural afterlife — nevertheless most likely have a sense of identity that does not easily accommodate the idea that our thoughts and feelings are influenced by bacteria. Indeed, such an idea might sound delusional.
Yet this is what is increasingly clearly understood: that the body is not the abode of an elusive self; nor that human experience can be reduced to the aggregation of cascades of action potentials producing a neural symphony; but that this seemingly unitary being is in fact a community in which what we are and what lives inside our body cannot be separated.
Science magazine reports: The 22 men took the same pill for four weeks. When interviewed, they said they felt less daily stress and their memories were sharper. The brain benefits were subtle, but the results, reported at last year’s annual meeting of the Society for Neuroscience, got attention. That’s because the pills were not a precise chemical formula synthesized by the pharmaceutical industry.
The capsules were brimming with bacteria.
In the ultimate PR turnaround, once-dreaded bacteria are being welcomed as health heroes. People gobble them up in probiotic yogurts, swallow pills packed with billions of bugs and recoil from hand sanitizers. Helping us nurture the microbial gardens in and on our bodies has become big business, judging by grocery store shelves.
These bacteria are possibly working at more than just keeping our bodies healthy: They may be changing our minds. Recent studies have begun turning up tantalizing hints about how the bacteria living in the gut can alter the way the brain works. These findings raise a question with profound implications for mental health: Can we soothe our brains by cultivating our bacteria?
By tinkering with the gut’s bacterial residents, scientists have changed the behavior of lab animals and small numbers of people. Microbial meddling has turned anxious mice bold and shy mice social. Rats inoculated with bacteria from depressed people develop signs of depression themselves. And small studies of people suggest that eating specific kinds of bacteria may change brain activity and ease anxiety. Because gut bacteria can make the very chemicals that brain cells use to communicate, the idea makes a certain amount of sense.
Though preliminary, such results suggest that the right bacteria in your gut could brighten mood and perhaps even combat pernicious mental disorders including anxiety and depression. The wrong microbes, however, might lead in a darker direction.
This perspective might sound a little too much like our minds are being controlled by our bacterial overlords. But consider this: Microbes have been with us since even before we were humans. Human and bacterial cells evolved together, like a pair of entwined trees, growing and adapting into a (mostly) harmonious ecosystem.
Our microbes (known collectively as the microbiome) are “so innate in who we are,” says gastroenterologist Kirsten Tillisch of UCLA. It’s easy to imagine that “they’re controlling us, or we’re controlling them.” But it’s becoming increasingly clear that no one is in charge. Instead, “it’s a conversation that our bodies are having with our microbiome,” Tillisch says. [Continue reading…]
