Gut Microbes Linked to Temperament Traits in Infants

By Traci Pedersen
November 24th, 2022
Medically reviewed by Paul Sietes, MD.

A new Finnish study of 303 infants finds that the gut microbiome of a two-month-old appears to be associated with the child’s temperament traits at six months of age.

The University of Turku researchers found that different temperament traits are connected with individual microbe genera, microbial diversity and different microbe clusters. For example, greater diversity in gut bacteria was connected to lesser negative emotionality and fear reactivity.

“It was interesting that, for example, the Bifidobacterium genus including several lactic acid bacteria was associated with higher positive emotions in infants,” said doctoral candidate Anna Aatsinki from the FinnBrain research project at the University of Turku, Finland.

“Positive emotionality is the tendency to experience and express happiness and delight, and it can also be a sign of an extrovert personality later in life.”

The study, published in the journal Brian, Behavior, and Immunity, is the first to investigate the link between microbes and behavior in infants so young. Previously, rodent studies have shown that the composition of gut microbiota and its remodelling is connected to behavior. In humans, research has shown that gut microbes can be associated with different diseases, such as Parkinson’s disease, depression and autism spectrum disorders. But few studies have been conducted on infants.

The new study also considered other factors that can significantly affect the diversity of the microbiota, such as the delivery method and breastfeeding.

Strong fear reaction and negative emotionality can be connected to depression risk later in life. However, the association with later diseases is not straightforward and   are also dependent on the environment.

“Although we discovered connections between diversity and temperament traits, it is not certain whether early microbial diversity affects disease risk later in life. It is also unclear what are the exact mechanisms behind the association,” Aatsinki said. “This is why we need follow-up studies as well as a closer examination of metabolites produced by the microbes.”

Source: University of Turku

Traci Pedersen is a professional writer with over a decade of experience. Her work consists of writing for both print and online publishers in a variety of genres including science chapter books, college and career articles, and elementary school curriculum.