Estimates of autism spectrum disorders have been increasing since Kanner (1943, 1944) pointed out an unusual cluster of affective symptoms in children. Specifically, epidemiological estimates have risen from 0.7 in 10,000 (Treffert, 1970) to as high as 1 in 150, as recently proffered by the U.S. Centers for Disease Control and Prevention (CDC; Department of Health & Human Services, 2007). Although the CDC cautions that their estimate is not a true national estimate, it is a remarkable finding, and if the estimates keep rising, they may eclipse prevalence estimates of intellectual disability in the United States, which are typically found to be slightly greater than 1% of the population (Braddock, Emerson, Felce, & Stancliff, 2001; Lee et al., 2001). If Treffert's estimate and the CDC estimate are both correct, one might conclude that autism has increased about 100-fold since 1970. An example of an actual...

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