As we close, we highlight five points. One concerns the very small number of Nathan and Gorman (2002)
Type 1 studies for young children with autism from which to draw conclusions. There is a low number of RCT studies, and these use small samples and examine different treatments with radically different delivery approaches and intensities, delivered over different time spans (12 weeks to 2 years), using different measurement approaches. One can generalize from these RCT studies that young children with autism, as a group, demonstrate accelerated developmental gains in response to focused daily interventions of several different kinds. Significant increases in language and communication abilities in the treated group occurred in most studies and interventions with many targeted hours per week resulted in increases in IQ at the group level as well. Reduction in severity of autism symptoms has also been reported.
Lack of comparative studies prevents us from answering questions concerning which comprehensive treatment approach is best for young children with autism, a question that requires a comparative RCT design with long-term follow-up data to answer. Given the many different characteristics seen in individual children and in various intervention approaches, the better question is, “Which teaching approaches appear most effective for teaching specific skills given certain profiles of child and contextual characteristics?”
Across all the studies we cited, improvements in language, communication, and IQ, and reduction in severity of autism symptoms indicate that the core symptoms of autism appear malleable in early childhood. Descriptions of recovery from several different treatment studies support the idea that some children who had autism early in life no longer demonstrate disability by school age or later. The proportion of treated children who may be capable of such outcomes is still unknown, and this is another area in which RCT designs are needed.
However, we must be cautious about overemphasizing the RCT design. Although the RCT design is the best methodology to answer some
questions, it is inappropriate for answering others. The RCT design has important limitations in early intervention studies of autism. In initial development of a new intervention, or in field trial work regarding effectiveness studies, the rigidity of an RCT design may interfere with the flexibility needed both in initial tests and in applications in the field, especially when considering the variation of features and behaviors within the autism spectrum (Schopler, 2005
). Further challenges in community-based trials may be encountered with respect to maintaining adherence to the rigid methodology of RCT design (e.g., controlling participant variables, randomized group assignments to treatment vs. control groups, single treatment approaches) while remaining ethically and legally aware of pertinent social, educational, and federally mandated policies.
A new intervention needs to be developed and tried with a few children and a few different treatment givers. Initial piloting of new intervention approaches may involve single-subject designs using a small number of participant and detailed qualitative analyses via case reports or pre–post designs to generate evidence of initial promise (Lord et al., 2005
). Such designs may not allow one to demonstrate a causal relationship between change and treatment, but they may provide some indication that an intervention appears useful and needs to be evaluated more rigorously, similar to the use of open-label trials of a new medication. Single-subject designs can test the causal relation between independent and dependent variables with small numbers of participant and short time periods. These designs are extremely helpful when evaluating efficacy of interventions that target only one or two behaviors. (See Smith et al. (2006
) for an excellent description of the stages of developing a new treatment and useful designs for evaluating each stage.)
An RCT design is a late-stage design, perhaps best used in autism for answering questions about the comparative effects of well-established complex interventions, those that require longer time periods to have effects. However, comparative studies are badly needed in autism intervention that are large and well powered enough to answer such questions. These are expensive studies to conduct and will require greater treatment research funding than has typically been awarded to autism studies.
Regardless of the design used, independent cross-site replications and longer term follow-up to examine maintenance and generalization are critical for documenting efficacy of an intervention. As in all areas of science, it is crucial that experimenters carefully match the study design with the question being asked.
The second point involves treatment efficacy. We have already identified Lovaas's intervention approach as one that meets the Chambless et al. (1996)
criteria for probably efficacious. Are there others? The work of Laura Schreibman, Lynn Koegel, and Robert Koegel using PRT to teach a variety of communication, language, play, and imitation skills deserves consideration. There is no specified curriculum for PRT, which involves a set of teaching practices rather than specific teaching content. However, there have been multiple publications of single-subject design studies demonstrating the efficacy of the PRT approach to teach these skills. Single-subject designs are classified as Type 2 studies according to the Nathan and Gorman (2002)
system. However, the number of published single-subject studies on PRT coming from different authors and different sites and including several that compare PRT to another treatment indicate that PRT also meets the Chambless et al. (1996)
criteria as a probably efficacious intervention (R. L. Koegel, Dyer, & Bell, 1987
; R. L. Koegel et al., 1988
; R. L. Koegel, O'Dell, & Koegel, 1987
; Schreibman, Kaneko, & Koegel, 1991
; see Delprato, 2001
, for a review of 10 comparative studies using a PRT type approach compared to a didactic approach).
Lack of strong designs and independent replications, or lack of any peer-reviewed published data at all, prevents other well-known autism treatments for meeting criteria as either well-established or probably efficacious treatments. There is currently a great need in autism intervention research for initial testing and replication of existing models. Other well-known interventions may be as or more efficacious as Lovaas's model or PRT, but they have not been rigorously evaluated.
Autism interventions are “branded” at this point in time. It can be quite helpful to the intervention field when a brand-name intervention provides empirically derived efficacy data for its approach and a well-written treatment manual for the public that specifies both the content to be taught (the curriculum) and the teaching procedures to be used. This provides an efficient “package” for early interventionists to implement compared to the laborious and time-consuming practice of assembling teaching plans derived from empirically supported practices for each of the Individual Educational Plans (IEPs) objectives a child might have.
There are several downsides to this branding of interventions, however. First, evaluating a comprehensive autism treatment as a whole package does not allow one to determine which of the many elements in a certain model are the ones responsible for change. Second, the branding immediately results in difficulties accessing the treatment, for treatment givers and for consumers. The press for well-publicized branded treatments can become an economic nightmare for families and schools, and the high demand for a treatment may result in increasing numbers of providers providing poor delivery of the brand-name program, compromising its possible benefits. Third, the packaging and publicizing of autism treatments may make it more difficult for parents and others to appreciate effective generic teaching practices. The desire for an effective treatment may become synonymous with a particular brand of treatment, and the brand-name issue may obscure the strengths of a very well-designed generic intervention plan for an individual child built on empirically sound practices and solid data. It would be helpful to the field for treatment givers to point out commonalities between the brand-name interventions and others, and to document empirically the specific generic efficacious practices underlying the effects in the brand-name program.
The third point involves how much improvement can be expected from the best of these interventions. It is clear that the developmental delays associated with autism can be reduced for some children in some areas by specific intervention approaches. The studies with the best outcomes demonstrate that as many as half of children show marked accelerations in developmental rate and perform within normal limits. Can early intervention produce recovery in autism? Recovery, defined by test scores in the normal range, regular successful school placement and performance, and lack of disability, occurs occasionally, both in intensively treated children and in comparison children. There is no evidence thus far from a Type 1 study that a treatment leads to recovery, but two Type 2 or Type 3 studies report recovery in a significant proportion of the treated sample (Howard et al., 2005
; McEachin et al., 1993
; Sallows & Graupner, 2005
). There appears to be the promise of “recovery” in autism, but we do not know how often recovery occurs. Until we have multisite studies with sufficient numbers to examine mediators and moderators of intervention effects, will we know the predictors of “recovery”?
The fourth point involves the lack of cultural considerations in autism intervention. Treatment programs have thus far been developed and evaluated primarily with children from European American backgrounds (Forehand & Kotchick, 1996
). Cultural issues may well moderate the effects of autism intervention programs. Variables including language barriers; different views on the etiology of autism; cultural differences in expectations regarding child independence, parental authority, and extended parental care; and stigma and shame associated with mental impairments that may interfere with the use of social, educational, and mental health services. Other barriers to service might relate to a family's socioeconomic status, such as not having access to a car to attain clinical services, or to cultural dissonance between the family and service provider. Because the majority of interventions summarized in this article did not include ethnically diverse participant groups, generalization of effects across groups is premature. Efforts to augment resources for culturally diverse populations must include systematic recruitment and comprehensive education and training programs designed to promote cultural competence among researchers and early service providers for young children with autism. Cultural and socioeconomic variables must be considered in intervention delivery to culturally diverse families (Santarelli, Koegel, Casas, & Koegel, 2001
To conclude this section, the kind of treatment research needed in autism may be unique, given the enormous scale of interventions needed. Treatment research in other areas of clinical child and adolescent psychology focuses on specific symptoms such as non-compliance, or disorders with a more limited set of symptoms than autism. Autism treatment needs to address every developmental area, all areas of adaptive behavior, and then a whole set of aberrant behavioral responses, involving both positive and negative symptoms. Even treatment for schizophrenia, or alcoholism, while needing to address multiple aspects of behavior, does not face the need to target every aspect of a person's life virtually from infancy on. Interventions for disorders of similar severity, such as addictions and schizophrenia, are often delivered in a protected and restricted setting, making measurement easier, while autism interventions require least restrictive environments, where it is hardest to do research. As can be seen from the studies just reviewed, the field is making progress, but the task is large and the obstacles are many.