
Johnson, 2004 reported that several research studies have documented the positive benefit of early intervention, particularly when help begins before the child is 3 years old.
Dawson, Osterling, 1997 reviewed eight interventional programs for children with autism and found that typically children who participate in one of these programs increase in IQ, and about half could be mainstreamed.
Children who start intervention early do better than children who start later, because the brain of a very young child has a better ability to develop when stimulated (Dawson, 2008; Mishori, 2008; Jensen, Sinclair, 2002).
Delaying early intervention for communication problems decreases a child's subsequent success. Some research shows that children with language problems in preschool are likely to face poor educational achievement at school age and are more likely to develop emotional and behavioral disorders.