title: A biochemical rationale for the interaction between gastrointestinal yeast and autism.
abstract: Autism is a disorder characterized by difficulty with social interactions, difficulty expressing empathy and intimacy and, in many cases, mild to severe language and learning deficits. Current estimates suggest autism now affects approximately one in 88 children, with rates increasing rapidly, making autism one of the most common and devastating developmental disorders. This trend is especially alarming considering that a cause for this disorder has yet to be discovered, nor are there successful biological treatments. Here a possible biochemical etiology is proposed for a certain spectrum of autism based on a reaction between propionic acid and ammonia released by Candida albicans in the gastrointestinal tract. A reaction between ammonia and propionic acid should result in the production of beta-alanine, a chemical similar in composition to gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter which has been shown to be present in higher quantities in autistic patients. Assuming beta-alanine is able to cross the blood-brain barrier, beta-alanine would be used in the brain as a partial antagonist, blocking the receptor sites for GABA, thus facilitating the production of more GABA to achieve equilibrium. An excess of GABA has been proposed as a possible contributor to autism. Further research should be conducted with this hypothesis to determine whether the chemical reaction in the human body between propionic acid and ammonia does in fact produce a chemical structurally and functionally similar to beta-alanine, as well as how this product affects the brain. Positive conclusions from this follow-on research could result in a preventative screening test for sensitivity to propionic acid and gastrointestinal yeast, thus slowing the progression of this type of autism. A more targeted treatment for children already diagnosed with autism could also result.
authors.affiliation: Psychology and Neuroscience Department, Duke University, Durham, NC, USA. caley.burrus@duke.edu
authors.forename: Caley J
authors.initials: CJ
authors.lastname: Burrus
mesh_terms: D001321:Autistic Disorder / Q000378:metabolism*; D002176:Candida albicans / Q000302:isolation & purification*; D041981:Gastrointestinal Tract / Q000382:microbiology*; D006801:Humans; D008962:Models, Theoretical