Our gut microbiota can influence our state of mind, including our mood and behaviour. In the recent issue of Cell, scientists reported that the compositional and structural shifts of microbes and associated metabolites can trigger autism spectrum disorder (ASD) symptoms. (2013, Cell 155,1451).
Neurodevelopmental disorders, including autism spectrum disorder (ASD), are defined by core behavioural impairments; however, subsets of individuals display a spectrum of gastrointestinal (GI) abnormalities.
We demonstrate GI barrier defects and microbiota alterations in the maternal immune activation (MIA) mouse model that is known to display features of ASD. Oral treatment of MIA offspring with the human commensal Bacteroides fragilis corrects gut permeability, alters microbial composition, and ameliorates defects in communicative, stereotypic, anxiety-like and sensorimotor behaviours.
MIA offspring display an altered serum metabolomic profile, and B. fragilis modulates levels of several metabolites. Treating naive mice with a metabolite that is increased by MIA and restored by B. fragilis causes certain behavioural abnormalities, suggesting that gut bacterial effects on the host metabolome impact behaviour. Taken together, these findings support a gut-microbiome-brain connection in a mouse model of ASD and identify a potential probiotic therapy for GI and particular behavioural symptoms in human neurodevelopmental disorders.
 Hsiao EY, McBride SW, Hsien S, Sharon G, Hyde ER, McCue T, Codelli JA, Chow J, Reisman SE, Petrosino JF, Patterson PH, Mazmanian SK. Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders. Cell. 2013 Dec 19;155(7):1451-63. doi: 10.1016/j.cell.2013.11.024. View Abstract