Biomarkers of Autistic Spectrum Disorder (ASD) refer to the aberrances in neurological and biological function in individuals diagnosed with ASD. Currently, ASD is diagnosed with a battery of clinical assessments of a child’s behavior, such as their level of engagement in social interaction, communication skills, and repetitive behaviors, when they are approximately 3-years-old or older. In addition to these hallmarks of ASD, researchers have identified atypicalities in some of the biological systems of individuals with ASD. Some of these differences may be indicative of a predisposition to developing autism, or even a marker of autism itself. It is the goal of biomarker research to identify the biological changes specific to ASD, thereby allowing researchers to develop more objective diagnostic tests, as well as allowing for earlier identification and intervention.
Review of Biomarker Research
The following paper provides an in-depth literature review of the research on biomarkers of ASDs.
Ratajczak, H. V. (2011). Theoretical aspects of autism: biomarkers – a review. Journal of Immunology, 8, 80-94.
Biomarkers in the Gastrointestinal System
Some research suggests that individuals with ASD may have differences in their gastrointestinal (GI) system, such as problems digesting certain foods. These GI abnormalities may be indicative of a predisposition to develop ASD.
Buie, T., Campbell, D., B., Fuchs, G. J. III, Furuta, G. T., Levy, J., Vandewater, J. et al. (2010). Evaluation, diagnosis, and treatment of gastrointestinal disorders in individuals with ASDs: A consensus report. Pediatrics, 125, S1-S18.
Hovarth, K., Papadimitriou, J. C., Rabsztyn, A., Drachenberg., C., & Tildon, J. T. (1999). Gastrointestinal abnormalities in children with autistic disorder. The Journal of Pediatrics, 135, 559-563.
Biomarkers in the Immunological System
It is possible that the immune system of individuals with ASD may be slightly different from that of their typically developing peers without a diagnosis. It is unclear whether these differences are linked to the development of ASD or a result of ASD.
Warren, R. P., Singh, V. K., Cole, P., Odell, J. D., Pingree, C. B., Warren, W. L., & White, E. (1991). Increased frequency of the null allele at the complement C4b locus in autism. Clinical and Experimental Immunology, 83, 438-440.
Much of the biomarker research has focused on levels of specific neurotransmitters in the brain of individuals diagnosed with ASD. These levels may be different in autism.
Auyeyng, B., Baron-Cohen, S., Ashwin, E., Knickmeyer, R., Taylor, K., & Hackett, G. (2009). Fetal testosterone and autistic traits. British Journal of Psychology, 100, 1-22.
Tordjman, S., Gutknecht, L., Carlier, M. et al. (2001). Role of the serotonin transporter gene in the behavioral expression of autism. Molecular Psychiatry, 6, 434-439.
Pardo, C. A., & Eberhart, C. G. (2007). The neurobiology of autism. Brain Pathology, 17, 434-447.
There is some evidence to suggest that ASD may affect the toxicological system, which is responsible for safely removing toxins from the body. The preponderance of this research is focused on the effects of oxidative stress on the biology of individuals with ASD.
James, S. J., Cutler, P., Melnyk, S., Jernigan, S., Janak, L., Gaylor, D. W., & Neubrander, J. A. (2004). Metabolic biomarkers of increased oxidative stress and impaired methylation capacity in children with autism. The American Journal of Clinical Nutrition, 80, 1611-1617.