Discovery of Brain Chemical Changes in Autism Could One Day Be Used to Reverse Process

Researchers have identified distinct brain chemical changes in children with autism spectrum disorder (ASD) that, they say, not only confirms it is fundamentally different from other developmental disorders, but could help scientists reverse the processes at play.

Led by a team from the University of Washington, the study compared brain chemistry among three groups of children: those with a diagnosis of autism spectrum disorder, those with a diagnosis of developmental delay and those considered to be developing in a typical manner.

They then used magnetic resonance spectroscopic imaging, a type of MRI, to measure tissue-based chemicals in three age groups, including 3 to 4 years old, 6 to 7 years old and 9 to 10 years old.

Among the chemicals measures was N-acetylaspartate, which is believed to play an important role in regulating synaptic connections and myelination, or the process by which a myelin sheath is formed. Its levels, studies have shown, are lower in people with conditions such as Alzheimer's, traumatic brain injury or stroke.

Other chemicals examined in the study -- choline, creatine, glutamine/glutamate and myo-inositol -- all help characterize brain tissue integrity and bioenergetic status, according to the scientists.

Among the study's notable discoveries was that while low concentrations of N-acetylaspartate were identified in 3-to-4-year-olds both with ASD and those identified as developmentally delayed, by age 9 and 10 these levels caught up to those of the typically developing group for the ASD cohort even as those in the developmentally delayed group continued to lag behind.

This pattern of chemical alterations that are then resolved is similar to those seen in people have suffered a closed head injury and then healed, the researchers explain, and offers new insight into how the life-altering disorder can be both detected and intervened on.

"A substantial number of kids with early, severe autism symptoms make tremendous improvements. We're only measuring part of the iceberg, but this is a glimmer that we might be able to find a more specific period of vulnerability that we can measure and learn how to do something more proactively," said Annette Estes, a co-author of the study and director of the UW Autism Center. Estes is an associate professor of speech and hearing sciences.

However, despite the encouraging finding, the researchers note that science has yet to identify exactly when and why autism really begins to take root, which is crucial because, as the study acknowledged, "even a relatively brief period of abnormal signaling between glial cells and neurons during early development would likely have a lasting effect" on how a child's brain network develops.

For this reason, the scientists are currently using more advanced MRI methods to study infants at risk for autism spectrum disorder because of an older sibling with autism.

"We're looking prospectively at these children starting at 6 months to determine if we can detect very early alterations in brain cell signaling or related cellular disruption that may precede early, subtle clinical symptoms of ASD," said Stephen R. Dager, a UW professor of radiology and adjunct professor of bioengineering and associate director of UW's Center on Human Development and Disability.