Numerous studies have reported a relationship between socio-economic status and the prevalence of Autism Spectrum Disorders. For example, in New Jersey, one of the wealthiest states in the United States, the prevalence of Autism Spectrum Disorders is 17.2 cases per 1000 children in homes with median incomes above $90,000 and only 7.1 cases per 1000 children in homes with median incomes less than $30,000.¹ This lower risk is probably due not to a protective effect of lower socio-economic status but rather to under diagnosis, a lack of surveillance by physicians, parents, and teachers, and reduced access to services. These disparities in diagnosis among socio-economic classes are not seen in European countries with universal access to medical care, suggesting that there is indeed a diagnostic bias against children of lower socio-economic status in the United States. ^2,3 

One recent study suggests that this socio-economic disparity in autism diagnoses is slowly starting to decrease.⁴ In this study of children with autism in California, the number of diagnoses of children from high-income homes is beginning to stall, and the diagnosis of children from lower-income homes is starting to increase. This increase seems to be due to the availability of diagnostic services provided to underprivileged children by the Medi-Cal system. These findings emphasize the importance of accessible diagnostic resources and services for all children with Autism Spectrum Disorders, especially those children from homes with fewer economic resources.