What is the prevalence of autism spectrum conditions?
In 2003, a detailed, federally supported study was published on the prevalence of autism spectrum conditions among children aged 3 to 10 years in metropolitan Atlanta. Using 1996 data, that study showed the prevalence for autism was 3.4 per 1000, with a male-female ratio of 4 to 1. The study did not show a major increase in autism compared to studies done in the 1980s and early 1990s. Whereas autism has traditionally been believed to occur in about 3 to 4 out of every 10,000 children, estimates of Asperger Syndrome have ranged from 20 or 25 to as high as 40 per 10,000. Studies commissioned by the California Legislature confirmed a sharp increase in the number of school-aged children with autism-related conditions in California. From 1998 to 2002, the number of documented California autism cases doubled from 10,360 to 20,377 according to a 2003 study. Extrapolating, this would mean at least 425,000 American children under 18 have some form of autism and over 3,000 San Franciscans are on
