Localization of White Matter Volume Increase in Autism and Developmental Language Disorder Herbert M,
Ziegler D, Makis N, Filipek P, Kemper T, Normandin J, Sanders H, Kennedy
D, Caviness V Abstract: Ann Neurol 55:530-540 2004 Findings Many studies have shown that in younger subjects brains of individuals with autism as well as with Developmental Language Disorder (DLD) tend to be larger than normal. The brain enlargment appears to be caused by abnormally large white matter volume. Dr. Ziegler and his colleagues studied individuals with autism, DLD, and controls with a brain scanning method that divided brain white matter into functional inner and outer zones. In both high-functioning autism and DLD nonuniformly distributed volume changes were observed: Enlargement was localized to the outer (radiate) white matter, whereas inner zone white matter compartments showed no volume differences from controls. It is known that radiate or outer white matter matures later than deeper white matter, and in both autism and DLD, this region showed greater volume increases than controls. This pattern of enlargement is consistent with the striking head enlargements developing in children with autism only after birth, in the first years of life.
Conclusions These findings suggest an ongoing postnatal process in both autism and DLD that is intrinsic to white matter changes. The striking similarity in the anatomical distribution of these changes suggests that these two disorders are on the same spectrum rather than distinct. Further characterizing these alterations in white matter can help guide the search for genetic or environmental factors that could alter these changes. This would help us to identify the triggers of these abnormal increase in white matter volume, which may ultimately lead to treatments to halt these brain changes
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