The overall objectives of early intervention in autism are to improve social function, communication, and other cognitive abilities and to reduce repetitive and obsessional behaviors, while also minimizing any adverse effects of the intervention. A comprehensive, systematic review with regard to efficacy and safety of different types of interventions has been presented by Parr.72
This review included (1) early multidisciplinary intervention programs, (2) dietary interventions, (3) drug treatments, and (4) nondrug treatments. Among programs referred to, the group of early multidisciplinary interventions (early intensive behavioral interventions [EIBIs], the Picture Exchange Communication System, More Than Words, and the TEACCH approach) were classified as likely to be beneficial, while most other programs (of those mentioned in the review) were found to be of unknown effectiveness. Among drugs, methylphenidate was found likely to be effective for hyperactivity.72
The evidence regarding the efficacy and safety of early interventions in autism is still limited.73
In a meta-analysis by Eldevik et al75
that involved nine controlled studies, a standardized mean difference effect size for two available outcome measures, change in full-scale intelligence and/or adaptive behavior composite, was demonstrated. In a meta-analysis by Virués-Ortega,76
comparable effects of ABA were reported. However, methodological issues, with regard to quality standards, such as various methods, designs, and treatment features were also discussed.
Most authors agree that EIBIs result in some improved outcomes in the short- and intermediate-term perspective,77
but there is considerable variability with EIBIs, being effective in subgroups of, but far from all, preschool children with autism. Despite the relative dearth of robust randomized controlled trial (RCT) evidence, there is limited consensus, based on clinical experience, that EIBIs are likely to be beneficial. In a recent Cochrane Database Systematic Review on EIBI for young children with ASDs it was concluded that there is some limited evidence that EIBI is an effective behavioral treatment for some children with ASDs.74
However, the current state of the evidence is limited because of the reliance on data from nonrandomized studies due to the relative lack of RCTs. Additional studies using RCT research designs are needed to draw conclusions about the effects of EIBI for children with ASDs.72
RCTs are often considered the gold standard in intervention studies. However, this view has recently been challenged specifically in relation to study design when it comes to children with complex developmental disorders such as autism.87
Moreover, in ASD intervention research using RCT techniques, children with major additional disabilities, coexisting medical disorders, epilepsy and/or severe IDs are usually excluded. This creates artificial conditions that are not representative of clinical reality. The present authors would like to add that RCTs alone cannot determine the long-term effectiveness of any intervention in disorders that are developmental in nature.
Given that there have not been any large scale studies regarding highly individualized interventions for autism, and the difficulty of integrating findings from RCTs – that can only really ever be performed with rigor over relatively brief periods of time – with those of essential naturalistic long-term outcome studies, the “evidence-basis” is limited and recommendations, by default, based more on clinical long-term experience than on “hard research fact.” Small-scale RCTs have provided some restricted evidence that ABA-based intensive interventions can be helpful for some young children with autism.86
Children in the EIBI programs usually receive 20–40 hours per week of intervention, and advantages with regard to outcome have been demonstrated with increased intensity, as reflected by a higher number of treatment hours per week.90
However, larger-scale naturalistic studies making use of these same ABA techniques or others have been unable to find any support for the intensity of the intervention being important in a positive way but that targeted, brief ABA interventions can improve social communication in young children with ASDs – to the same degree as more intensive interventions.71
Many outcome studies have highlighted the importance of the child’s IQ. This factor has been demonstrated to have a very strong and independent influence on outcome with regard to adaptive functioning, quite regardless of the intensities of the intervention given.71
In a retrospective study it was reported that preschool children with autism, without ID, who had received early ABA treatment had improved considerably with regard to both IQ and adaptive functioning.95
These preliminary findings need to be replicated in prospective RCTs and naturalistic studies before any conclusions can be drawn.
Some Swedish outcome studies, carried out before the introduction of early intervention programs, have revealed a poor prognosis for many individuals with ASDs. In a prospective long-term follow-up study, 120 individuals diagnosed in childhood were reevaluated at ages between 17 and 40 years with regard to outcome based on employment, higher education or vocational training, independent living, and peer relationships. Overall outcome was found to be poor in 78% of cases. Only four individuals were independent, albeit leading fairly isolated lives. Childhood IQ level was positively correlated with better adult outcome, as was the existence of some communicative phrase speech at the age of 6 years.96
A similar prognosis, with 59% showing a poor or very poor outcome, was also reported in a previous Swedish study.97
In a prospective follow-up study of 70 males with Asperger’s syndrome and 70 males with autism, outcome was found to be good in 27% of those with Asperger’s syndrome; however, a similar proportion was found to live a very restricted life, with no occupation or activity and no friends. Outcome in the autism group was significantly worse.98
Howlin et al’s99
systematic review of controlled studies of EIBIs for young children with autism showed that at group level, EIBI resulted in improved outcomes (primarily measured by IQ) compared with comparison groups. At an individual level, however, there was considerable variability in outcome, with some evidence that initial IQ (but not age) was related to progress. The review provides some evidence for the effectiveness of EIBI for some, but not all, preschool children with autism. Reichow’s100
overview of five meta-analyses shows that, on average, EIBI can be a powerful intervention capable of producing large gains in IQ and/or adaptive behavior for many young children with ASDs.
Ospina et al’s101
review concludes that no definitive behavioral or developmental intervention improves all symptoms for all individuals with ASDs, and the authors recommended that clinical management should be guided by individual needs and availability of resources.
In a review by Warren et al102
that covers studies from 2000 to 2010, some evidence was found to support the argument that early intensive behavioral and developmental intervention is beneficial for improving cognitive performance, language skills, and adaptive behavior in certain groups of children with autism. The authors highlighted both the need for replication and the importance of clinical characterization of the children who are the ones most likely to benefit from intensive interventions. It was pointed out that there are many factors that need to be better studied, including modifiers of effectiveness, generalization of effects outside the treatment context, and predictors of treatment success.102
In a systematic review of RCTs or quasi-randomized controlled studies by Spreckley and Boyd,103
outcome after applied behavior intervention or standard care in young children with ASDs was compared. The authors found no evidence that applied behavior intervention gave better outcome than standard care.103