Urinary p-cresol is elevated in small children with severe autism spectrum disorder

Abstract

Several studies have described in autistic patients an overgrowth of unusual gut bacterial strains, able to push the fermentation of tyrosine up to the formation of p-cresol. We compared levels of urinary p-cresol, measured by high-performance liquid chromatography–ultraviolet, in 59 matched case-control pairs. Urinary p-cresol was significantly elevated in autistic children smaller than 8 years of age (p < 0.01), typically females (p < 0.05), and more severely affected regardless of sex (p < 0.05). Urinary cotinine measurements excluded smoking-related hydrocarbon contaminations as contributors to these differences. Hence, elevated urinary p-cresol may serve as a biomarker of autism liability in small children, especially females and more severely affected males.

Keywords::

• Clostridium
• cotinine
• gut flora
• organic contaminants
• pervasive developmental disorders

Acknowledgements

The authors gratefully acknowledge all the families who participated in this study.

Declaration of interest

This work was supported by the Italian Ministry for University, Scientific Research and Technology (PRIN no. 2006058195 and no. 2008BACT54_002), the Italian Ministry of Health (RFPS-2007-5-640174), and the Autism Speaks Foundation (Princeton, NJ).