According to the Autism and Developmental Disabilities Monitoring, an active surveillance system network that estimates the prevalence of ASDs from 14 sites in the USA, the overall prevalence of ASDs during 2008 was 1 in 88 children. Their data suggest that the prevalence of autism spectrum disorder between 2000 to 2008 has been increasing (see table). This increase could be an indication that autism awareness and access to services have somewhat improved, but also attests to the need for more programs serving this population.
Dr. Paul Patterson in his new book, Infectious Behavior: Brain-Immune Connections in Autism, Schizophrenia, and Depression (2011) tries to elucidate this trend in prevalence and decode some of the multiple hypotheses on the etiology of Autism Spectrum disorders. In addition to the behavior symptoms and genetic components in autism, Dr. Patterson studies the role of the neuro-immune system abnormalities and interactions, fetal testosterone levels and the maternal infection risk factor. The notion that maternal infection constitutes a risk factor of development of autism has been supported by Dr. Stell Chase, which reported the first incidence of autistic features in 1964. According to Dr. Patterson, the autistic features outcome may be more frequent if infections occur early in the first trimester. It has been reported in the literature that the timing of infections is critical for fetal brain development, which may lead to adverse postnatal behavioral outcomes (Pardo & Eberhart, 2007).
Several studies have linked Autism Spectrum Disorders (ASD) with maternal viral, bacterial, and protozoan infections, which are hypothesized to evoke an immune response in the pregnant women that may predispose her offspring to autism. Another hypothesis is that elevated testosterone may impact fetal brain development that may lead to autistic traits and gender bias. This hypothesis supports the fact that prevalence is highest in males than females. There is much that we have yet to learn about Autism Spectrum Disorder, and it’s reassuring that the Combating Autism Reauthorization Act of 2011was extended to further our research on this important disorder.