Brain chemical changes in autism identified

Common etiology ID'd for autism, schizophrenia, bipolar disorder
Common etiology ID'd for autism, schizophrenia, bipolar disorder

HealthDay News -- Children with autism spectrum disorders (ASD) experience changes in the levels of certain chemicals in brain gray matter between 3 and 10 years of age that can distinguish them from children with other forms of developmental delay, study findings suggest.

Compared with typically developing children, those with an ASD had lower levels of N-acetylaspartate, choline and creatine in both gray and white matter at age 3 to 4 years, but not at 9 to 10 years, Stephen Dager, MD of the Unviersity of Washington in Seattle, and colleagues reported in JAMA Psychiatry.

In contrast, children in the developmental delay group had lower levels of N-acetylaspartate in both gray and white matter at age 3 to 4 years, which remained lower in the gray matter at 9 to 10 years compared with typically developing children.

"The results from our study suggest that a dynamic brain developmental process underlies ASD, whereas the children with developmental delay exhibited a different, more static developmental pattern of brain chemical changes,"  the researchers wrote. "The brain chemical alterations observed in the children with ASD at 3 to 4 years of age likely reflect a process that begins at an earlier stage of development."

To better understand the underlying pathophysiology of ASD, Dager and colleagues measured the levels of N-acetylaspartate, choline, creatine, myo-inositol and glutamine plus glutamate in cerebral gray matter and white matter in three groups of children:

  • 73 children aged 3 to 4 years, including 45 with an ASD, 14 with developmental delays and 14 with typical development
  • 69 children aged 6 to 7 years, including 35 with an ASD, 14 with developmental delays and 20 with typical development
  • 77 children aged 9 to 10 years of age, including 29 with an ASD, 15 with developmental delay and 33 with typical development.

Compared with typically developing children, the researchers found that children with autism spectrum disorder had lower levels of N-acetylaspartate, choline and creatine in both gray and white matter at 3 to 4 years of age, but these lower concentrations were no longer observed at age 9 to 10 years. In particular, N-acetylaspartate concentrations rebounded to nearly normal levels.

The developmental delay group also had lower levels of N-acetylaspartate in both gray and white matter at 3 to 4 years of age compared with typical children, but levels remained lower in gray matter through age 10 years.

Brain chemical changes in children with ASD are similar to those seen in other disorders, such as multiple sclerosis, epilepsy and traumatic brain injury, in which N-acetylaspartate levels are low at the time of onset but rebound with treatment or recovery.

The increased in N-acetylaspartate levels to nearly normal levels among children with ASDs may indicate "a dynamic and recoverable disease process that can result in other downstream effects but does not, in itself, persist over time," the researchers suggested.

Several study limitations include the relatively small number of children with typical development included in the youngest age group and the cross-sectional design of the analysis of typical children, they noted.


References

  1. Corrigan NM et al. JAMA Psychiatry. 2013; doi:10.1001/jamapsychiatry.2013.1388.
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