The following information is taken from a July, 2011 information update on the Health Canada web site. It indicates that recent studies have found that "children whose mothers took a valproate drug tend to score lower on cognitive (intelligence) tests than children whose mothers who took other anti-epileptic medications during pregnancy."
The release also indicates, somewhat more ambiguously, that "Product labelling for both Depakene and Epival [valproate drug brands sold in Canada] contain information on the risk of birth defects (e.g., spina bifida), as well as the risk of developmental delay, autism and/or autism spectrum disorders." It would be helpful if Health Canada explained exactly what that statement was supposed to mean.
The abstract of a study reported in 2005 is somewhat clearer. In Arndt TL, Stodgell CJ, Rodier PM (2005). "The teratology of autism". Int J Dev Neurosci 23 (2–3): 189–99. doi:10.1016/j.ijdevneu.2004.11.001. PMID 15749245 it states that:
"Autism spectrum disorders affect behaviors that emerge at ages when typically developing children become increasingly social and communicative, but many lines of evidence suggest that the underlying alterations in the brain occur long before the period when symptoms become obvious. Studies of the behavior of children in the first year of life demonstrate that symptoms are often detectable in the first 6 months. The environmental factors known to increase the risk of autism have critical periods of action during embryogenesis. Minor malformations that occur frequently in people with autism are known to arise in the same stages of development. Anomalies reported from histological studies of the brain are consistent with an early alteration of development. Congenital syndromes with high rates of autism include somatic that originate early in the first trimester. In addition, it is possible to duplicate a number of anatomic and behavioral features characteristic of human cases by exposing rat embryos to a teratogenic dose of valproic acid at the time of neural tube closure."
"Autism spectrum disorders affect behaviors that emerge at ages when typically developing children become increasingly social and communicative, but many lines of evidence suggest that the underlying alterations in the brain occur long before the period when symptoms become obvious. Studies of the behavior of children in the first year of life demonstrate that symptoms are often detectable in the first 6 months. The environmental factors known to increase the risk of autism have critical periods of action during embryogenesis. Minor malformations that occur frequently in people with autism are known to arise in the same stages of development. Anomalies reported from histological studies of the brain are consistent with an early alteration of development. Congenital syndromes with high rates of autism include somatic that originate early in the first trimester. In addition, it is possible to duplicate a number of anatomic and behavioral features characteristic of human cases by exposing rat embryos to a teratogenic dose of valproic acid at the time of neural tube closure."
Given the huge imbalance of autism research funding that overwhelmingly favors genetic research over environmental focused autism research it is amazing that the autism paradigm shift which emphasizes the interaction of genetic and environmental factors is taking place. It is encouraging to see research of possible environmental factors particularly studies that examine possible prenatal causes of autism disorders.
