.. the science behind behavioral treatments is modest at best. Researchers have published very few rigorously controlled studies of the therapies, and the results of those studies have been mixed. While some children thrive, even joining regular classrooms, the studies have found that most show moderate or little improvement....
The most recent analysis of treatment research, financed by the National Institutes of Health and scheduled to be published next year, concludes that although behavior treatments benefit many children, there is no evidence that any particular treatment leads to recovery. Doctors do not yet know how to predict which children will improve in the treatments, or even how treatable the condition is, the report concludes.
'If so many kids are being cured, then where are they? Who are they? Show me 10 percent,' said Dr. Bryna Siegel, director of the autism clinic at the University of California, San Francisco. 'The reason practitioners can't show you all these kids is because there simply aren't that many of them out there.'
We need better science, and we need to be skeptical. Even if these interventions weren't expensive, they'd still ask a lot of parents and families, and they limit the opportunity to pursue other treatments (though I don't know of any alternatives!).