Biomarkers

Currently, autism 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 autism, researchers have identified atypicalities in some of the biological systems of individuals with autism. 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 autism, thereby allowing researchers to develop more objective diagnostic tests, as well as allowing for earlier identification and intervention.

Review of biomarker research
A 2011 paper in the Journal of Immunotoxicology provides an in-depth literature review of the research on biomarkers of autism¹.

Biomarkers in the gastrointestinal system
Some research suggests that individuals with autism may have differences in their gastrointestinal (GI) system, such as problems digesting certain foods^2,3. These GI abnormalities may be indicative of a predisposition to develop autism.

Biomarkers in the immunological system
It is possible that the immune system of individuals with autism may be slightly different from that of their typically developing peers without a diagnosis⁴. It is unclear whether these differences are linked to the development of autism or a result of the condition.

Neurological biomarkers
Much of the biomarker research has focused on levels of specific neurotransmitters in the brains of individuals diagnosed with autism^5,6,7. These levels may be different in autism.

Toxicological biomarkers
There is some evidence to suggest that autism 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 autism⁸.