The original estimates of the prevalence of autism indicated that it occurred in around 2 per 10,000 people. However, recent estimates place the prevalence as high as or higher than 1 in 36 children for all autism spectrum disorders combined according to The Centers for Disease Control and Prevention (CDC). It is likely that the increased prevalence of autism is due to increased awareness of the disorder by the population at large as well as by physicians and other providers of service to children and better diagnostic tools that more accurately covers the entire autism spectrum. There is some evidence that suggests that mental retardation is being given as a primary diagnosis less often than in the past. The increased prevalence of autism coincides with this decrease. However, a true increase in the prevalence of autism across time is certainly possible.
