Your personality may change based on the health of this part of your body

It’s hard to believe that the tiny little organisms living in our digestive tracts are responsible for so many important physiological outcomes—despite the abundance of research confirming as much.

Among the medical community, these microorganisms are known as human gastrointestinal microbiota and when curated correctly they make up our happy healthy gut community.

Ladders has covered the impact gut bacteria has on chronic disease on several occasions, (available here) but literature has been hitherto limited in terms of its effect on behavioral and emotional health.

A new paper published in the Human Microbiome Journal sets out to rectify this deficit.

“The gut microbiome has a measurable impact on the brain, influencing stress, anxiety, depressive symptoms and social behaviour.  This microbiome–gut–brain axis may be mediated by various mechanisms including neural, immune and endocrine signalling,” the authors report. “Here the composition and diversity of the gut microbiome is investigated with respect to human personality. Using regression models to control for possible confounding factors, the abundances of specific bacterial genera are shown to be significantly predicted by personality traits.”

Gut microbiome composition and diversity are related to human personality traits

The pioneering research was led by Dr. Katerina Johnson, of Oxford University.

In the recent past, Dr.Johnson’s studies have been focused on the microbiome-gut-brain axis and its potential to provide unconventional insights into variations in social behavior and personality.

Not only do subtle adjustments in gut bacteria activity yield drastic alterations to one’s internal chemistry, but subtle dietary changes similarly yield drastic changes to the diversity of one’s gut community.

Little things like being fed formula as a baby affects gastrological and neurological ripples late in life.

After a meta-review of previous research conducted on animals models, Dr. Johnson and her team established these four main findings:

  1. Analyses targeted bacterial genera linked to behavior in animal and human psychiatric studies.
  2. Bacterial genera were modeled (using negative binomial regression) with respect to personality.
  3. Genera linked to autism are also related to social behavior in the general population.
  4. Sociability is associated with higher diversity and anxiety and stress with reduced diversity.

There are plenty of nuances to explore with each of the pillars above, but on balance, the more diverse one’s gut community is the more sociable one tends to be.

Conversely, a homogeneous gut community has been linked to a series of neuropsychiatric conditions.

In service of a paper published in the journal Nature earlier this year, researchers placed a crop of mice on a germ-free regimen that resulted in a community lacking the typical mix of gut microbes.

These mice began to demonstrate antisocial behavior soon thereafter.  They avoided other mice, shunned new situations, and groomed themselves excessively.

The authors were confident that our psychology is sensitive to the existence of a gut-brain axis, in which gut microbes produce bioactive compounds.

Dr. Johnson’s research, published a few short months after, reconfirms this appreciation of the available data set. This very same data set additionally suggested compelling correlative relationships between gut–brain axis and the development of physiological conditions like major depression.

“This suggests that the gut microbiome may contribute not only to the extreme behavioral traits seen in autism but also to variation in social behavior in the general population,” Johnson concludes. “Future research may benefit from directly investigating the potential effect these bacteria may have on behavior, which may help inform the development of new therapies for autism and depression.”