Autism spectrum disorder (ASD) is a complex developmental disability that impairs social interaction and communication. A child with autism has difficulty interacting with others, shows little interest in others, and lacks social awareness. Autism is more prevalent among boys than girls, with the ratio estimated at 4:1. Autism is a multifactorial disorder; several factors must be considered when determining the case. These factors include complex genetic interactions, nutritional deficiencies or overloads, pre- and postnatal exposure to chemicals or viruses, errors during the embryonic neural tube closure process, dysfunctional immune systems, and allergies. Recent studies have correlated gut dysfunction with ASD and suggest a possible role of the gastrointestinal (GI) microflora in symptomatology and or severity of symptoms in autistic children. Many autistic children experience severe dietary or GI problems including abdominal pain, constipation, diarrhea, and bloating. These symptoms may be due to the disruption of the indigenous gut flora promoting the overgrowth of potentially pathogenic microorganisms.
A growing body of medical research indicates that alterations in the type of bacteria that live in the GI tract can influence brain function, mood and overall mental health. Recently, Hsaio and colleagues (2013) linked gut microbes to ASD in a mouse model. They showed that ASD symptoms are triggered by compositional and structural shifts of microbes and associated metabolites. More importantly, they provided some of the first conclusive evidence of reversing symptoms of ASD via administration of Bacteroides fragilis probiotic. The broader potential of this research is identifying an analogous probiotic that can treat subsets of individuals with ASD; probiotics may provide therapeutic strategies for neurodevelopmental disorders. Therapies that target the gut microbiome may hold the key for making progress against a wide range of notoriously difficult psychiatric illnesses.
In a new study from Finland, Pärtty and colleagues (2015) are the first to show that probiotic supplementation early in life may be effective for reducing attention deficit hyperactivity disorder (ADHD) and ASD in children.
Researchers in Finland tested the hypothesis that probiotic supplementation may protect against the development of ADHD and AS by reviewing data from a study that was originally designed to test the effect of early supplementation with a probiotic in infancy on the later development of eczema. The mothers of 159 children were recruited in a randomized, double-blind, placebo-controlled study and received 10 billion colony-forming units of Lactobacillus rhamnosus or placebo daily for 4 weeks before expected delivery. After delivery, the capsule contents were given either to the children or continuously to the mothers (if breast-feeding) for 6 months.
To evaluate the possible link between probiotic supplementation and ADHD or AS, 75 of these children were evaluated by an experienced third party child psychiatrist or neurologist and the children were randomized and blinded so as not to produce any study bias. Results showed that ADHD or AS was diagnosed in 6/35 (17.1%) children in the placebo and none in the probiotic group (0/40). The probability value of this occurring was 0.008, indicating that it was not due to chance, but rather to a clear effect.
Previously stored fecal samples allowed the researchers to analyze the children for gut bacteria during their first six months of life. The researchers found that the numbers of Bifidobacterium species bacteria in feces during the first 6 months of life was lower in children with ADHD and AS compared to the healthy children.
The researchers concluded “Probiotic supplementation early in life may reduce the risk of neuropsychiatric disorder development later in childhood possible by mechanisms not limited to gut microbiota composition.”
Gilbert JA, Krajmalnik-Brown R, Porazinska DL, Weiss SJ, Knight R. 2013. Toward Effective Probiotics for Autism and Other Neurodevelopmental Disorders. Cell 155(7):1446-1448.
Hsaio EY, McBride SW, Hsien S, Sharon G, Hyde ER, McCue T, Codelli JA, Chow J, Reisman SE, Petrosino JF, et al. 2013. Cell 155(7):1451–1463.
Kaluzna-Czaplinska J, Blaszczyk S. 2012. The level of arabinitol in autistic children after probiotic therapy. Nutrition 28:124-126.
Pärtty A, Kalliomäki M, Wacklin P, Salminen S, Isolauri E. 2015. A possible link between early probiotic intervention and the risk of neuropsychiatric disorders later in childhood: a randomized trial. Pediatr Res. doi: 10.1038/pr.2015.51.