Temperament in early childhood is associated with gut microbiota composition and diversity

Temperament is a key predictor of human mental health, and cognitive and emotional development. While human fear behavior is reportedly associated with gut microbiome in infancy, infant gut microbiota changes dramatically during the first five years, when the diversity and composition of gut microbiome are established. This period is crucial for developing human executive functioning, including emotion regulation. Therefore, this study investigated the relationship between temperament and gut microbiota in 284 preschool children aged 3-4 years. Child temperament was assessed by maternal reports of the Childrens Behavior Questionnaire. Gut microbiota (alpha/beta diversity and genera abundance) was evaluated using 16S rRNA sequencing of stool samples. A high abundance of anti-inflammatory bacteria (e.g., Faecalibacterium) and low abundance of inflammatory bacteria (e.g., Eggerthella, Flavonifractor) were associated with higher positive emotionality and reward-seeking (i.e., Surgency/Extraversion, {beta} =0.15, p = 0.013), and lower negative emotionality and behavioral inhibition (i.e., Negative Affectivity, {beta} = -0.17, p = 0.004). Additionally, gut microbiota diversity was associated with a more active approach and exploration (i.e., Impulsivity, a specific aspect of Surgency/Extraversion, {beta} = 0.16, p = 0.008). This study provides insight into the biological mechanisms of temperament and takes important steps toward identifying predictive markers of psychological/emotional risk.