The current issue of Biological Psychiatry contains seven autism-related articles, along with a commentary by Autism Speaks Scientific Advisory Committee member Daniel Geschwind, M.D., Ph.D. These articles report findings on a wide range of autism issues, including brain activity patterns, brain chemistry, visual processing, olfactory and taste perception, and a new "macrosomic" subgroup in autism [Read about this subgroup from an article featured in our Oct. 18 e-Speaks].
Here we highlight two other articles that tentatively identify biological markers for autism. Finding biological markers is crucial for detecting autism earlier, before behavioral signs are present.
The first article reports the first-ever ultrasound study of fetal brain size in autism. Although researchers are now identifying the first signs of autism in infancy, this study attempted to look even earlier by searching for markers of autism in the womb using retrospective examination of fetal ultrasounds. Led by Dr. Janet Lainhart, M.D., at the University of Utah, researchers found that midgestational (~20 weeks) measurements of fetal brain and body size were normal on average in those children who later developed autism. However, a subset exhibited a smaller fetal body size: those later diagnosed with autism that came from families with more than one affected individual ("multiplex") had a decreased abdominal circumference relative to those from families with only one affected member ("simplex") and to controls. This finding further differentiates multiplex from simplex cases of autism, and supports the idea of subgroups within autism. Anatomical differences such as this could potentially flag those fetuses at risk for developing autism, and the innovative use of fetal ultrasound in this study could expedite discovery of any prenatal signs of autism.
The second article reports an intriguing observation about the immune system in autism. Immunological molecules known as "cell adhesion molecules" were measured in subjects with autism by a team of Japanese scientists headed by Dr. Kenji Hashimoto, Ph.D. These molecules are used by the immune system to adhere to targets during inflammatory responses, and their levels are altered in inflammation-related diseases. This study found that male subjects with high-functioning autism had lower levels of platelet-endothelial adhesion molecule (PECAM-1) and vascular cell adhesion molecule (VCAM-1) in their blood compared to male, age-matched controls. Also, low levels of PECAM-1 were correlated with large head size at birth in subjects with autism, suggesting that this molecule could somehow be related to the brain anomalies that characterize autism. While it is unclear what these decreased levels of cell adhesion molecules signify, they may also potentially serve as a biological marker for autism. Finding these markers is critical because they could hasten diagnosis, resulting in early treatment and better outcomes for people with autism.