The effectiveness of applied behaviour analysis interventions for people with Autism Spectrum Disorder

Publication Details

This systematic review considers the evidence for the effectiveness of interventions grounded in the principles of applied behaviour analysis for people with autism spectrum disorder.

Released on Education Counts: April 2010

Author(s): Marita Broadstock and Anne Lethaby, New Zealand Guidelines Group.

Date Published: 19 December 2008

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Background

Following the New Zealand Government review of autism services in 1998 (‘the Curry Report’), the Ministry of Education and Ministry of Health (‘the Ministries’) sponsored and funded the development of a New Zealand Autism Spectrum Disorder (ASD) Guideline. A draft was released for consultation in December 2006 and feedback was sought from across the health, education, disability and social service sectors, as well as from individuals and families affected by ASD. A number of the submissions related to the use of Applied Behaviour Analysis (ABA). Some literature relating to ABA interventions was nominated by submitters in the consultation process (Ministries of Health and Education 2007).

In response to comments received, the Ministries put out an an open Request for Tender (RFT) for an independent, systematic review of published research on the effectiveness of applied behaviour analysis interventions for people with ASD. Two review groups were contracted by the Ministry of Education to provide parallel reviews, the New Zealand Guidelines Group (NZGG), and a team of New Zealand academics with expertise in ABA, led by Dr. Oliver Mudford (University of Auckland).

The findings from both reviews will be considered by the ASD cross government Senior Officials Group (the Senior Officials Group) and, where they identify implications for the current Guideline on ASD (Ministries of Health and Education 2008), these will be considered by the ASD Living Guideline Working Group (LGWG).

Autism Spectrum Disorder

ASD is a group of pervasive developmental disorders that affects communication, social interaction and adaptive behaviour functioning. Generalising from recent overseas data, ASD is thought to affect more than 40,000 New Zealanders (Ministries of Health and Education 2008).

Subgroups of ASD include Pervasive Developmental Disorders (PDD), classical autism, Asperger syndrome, and Pervasive Developmental Disorders – Not Otherwise Specified (PDD-NOS) (as defined in ICD-10 and DSM-IV diagnostic manuals).

Core features of people diagnosed with ASD are evident in three areas:

  • impairment in the ability to understand and use verbal and non-verbal communication;
  • impairment in the ability to understand social behaviour, which affects their ability to interact with other people;
  • impairment in the ability to think and behave flexibly which may be shown in restricted, obsessional or repetitive activities.
Associated features of ASD may include:
  • severe problem behaviours, such as tantrums, self-injury, and
     aggressive behaviour;
  • attention and concentration problems;
  • sleep disturbance;
  • unusual responses to sensory stimuli;
  • special skills and interests, such as a talent for music, mathematics,  visual-spatial abilities, or an exceptional memory for areas of  knowledge of particular interest;
  • an outstanding rote visual or auditory memory and a high intelligence  quotient (IQ) for some individuals. 
There is a diverse range of disability and intellectual function expressed by people with ASD, from severe impairment of a person with classical autism, to a ‘high functioning’ person with Asperger syndrome. A wide range of intervention and supportive care services and approaches are required to reflect the heterogeneity of the condition. 

Applied Behaviour Analysis

Behavioural interventions have been variously described as involving the use of applied behaviour analysis, positive behaviour support, behaviour modification, behavioural programming, etc. Behavioural interventions are typically applied as a treatment package that can often include a diverse range of assessment and intervention procedures. However, all behavioural interventions are based on the science of Applied Behaviour Analysis (Ministries of Health and Education 2008), an applied science that focuses on the causes of socially significant behaviour change.

ABA-based interventions can be defined as ‘those in which the principles of learning theory are applied in a systematic and measurable manner to increase, reduce, maintain and/or generalise target behaviours’ (Ministries of Health and Education 2007). Well-established principles and techniques of ABA include (a) reinforcement,  b) shaping, (c) chaining, (d) fading, (e) response and stimulus prompting, (f) discrimination training, (g) programming, and (h) functional assessment.

The recently released New Zealand ASD Guideline (Ministries of Health and Education 2008) considers ABA approaches in relation to teaching and learning of adaptive behaviours (eg, communication skills, social skills, daily living skills), and replacement of challenging behaviour. The Guideline introduces ABA approaches in people with autism, defining early ABA research as that which used instructional techniques such as discrete trial training (DTT), as used in the Lovaas Young Autism Project (Lovaas 1987). In DTT, a task or trial is isolated and taught by repeated presentations to an individual, with successes reinforced and responses recorded, until the individual has demonstrated mastery. Interventions such as Early Intensive Behavioural Intervention (EIBI) and Intensive Behavioural Intervention (IBI) often use a discrete trial format in combination with more naturalistic teaching arrangements. Contemporary ABA approaches include procedures such as pivotal response training, incidental teaching, naturalistic teaching and milieu teaching. These have often been conducted in the context of functional routines (eg, requests for preferred foods are taught during lunch, requests for prefered toys are taught during play) (Prizant and Wetherby 1998).

With respect to problem behaviours, the Guideline (Ministries of Health and Education 2008) explicitly endorses ABA approaches: “behaviour management techniques should be used to intervene with problem behaviours” (Recommendation 4.3.4). Further, it recommends, “all behavioural interventions should be of good quality and incorporate the following principles: person-centred planning, functional assessment, positive intervention strategies, multifaceted interventions, focus on environment, meaningful outcomes, focus on ecological validity and systems-level intervention” (Recommendation 4.3.5).

Where the ASD Guideline (Ministries of Health and Education 2008) considers interventions aimed at addressing challenging behaviour in education settings, it advises that “educational interventions should incorporate principles of positive behaviour support, particularly a focus on understanding the function of the child’s behaviour” (Recommendation 3.2.5.2). This approach is reflected in functional analysis or assessment, an ABA-grounded approach based on evidence that problem behaviours are often maintained by reinforcement contingencies. This also applies to challenging behaviours. Functional assessments attempt to identify variables that reliably evoke and maintain the problem behaviour. More appropriate behaviours are then identified and taught in an attempt to replace the problematic behaviour, or the environment can be modified to eliminate the triggers for the behaviour (Ministries of Health and Education 2008). 

Functional communication training (FCT) is an ABA-based approach which aims to identify the communicative function of a (problem) behaviour and then replace the problem behaviour by teaching communication skills that serve the same function or purpose as the problem behaviour.

The ASD Guideline (Ministries of Health and Education 2008) also identifies the Picture Exchange Communication System (PECS) as a prominent intervention to promote initiation of non-speech communication. PECS is based on ABA principles, including the use of response prompting, prompt fading and differential reinforcement. With PECS, individuals are initially taught to exchange stimulus, response and reward. People are encouraged to exchange picture symbols to communicate. 

Video modelling is also highlighted in the Guideline (Ministries of Health and Education 2008). It is based on the ABA principle of modelling, where a video image is used to convey meaningful information or correct performance of an action, by either presenting images of peers, actors, or (in video self modelling) edited footage of the targeted individual.

Overall, the ASD Guideline (Ministries of Health and Education 2008) does not favour any particular educational intervention:

“There is no evidence that any single model is effective for teaching every  goal to all children with ASD. Models should be chosen to fit the  characteristics of the child and the learning situation” (Recommendation  3.1.2).

It further advises, “decisions about the type of intervention and the degree of intensity should be informed by a skilled team and reflect the child’s developmental stage, characteristics, teaching goals and family preferences” (Recommendation 3.1.3). Whilst the Guideline suggests that programme intensity is required for children aged under eight years with ASD, it is not able to recommend an optimal amount of intensity. It notes under ‘Implications for practice’ (Section 3.1.c) that “the quality of the intervention/education is at least as important as its intensity” (page 91).

With respect to management of ASD using psychological approaches, the Guideline recommends that, “the feasibility of establishing publicly funded, ASD-specific behavioural services should be investigated” (Recommendation 4.3.7).

Scope of Review

The review scope was developed by NZGG based on that defined in the Ministries’ RFT (2007) and modified in consultation with the Senior Officials Group. It was agreed that, consistent with NZGG’s expertise, NZGG’s review would be restricted to primary research employing group designs, and secondary research (of various study designs) meeting other agreed selection criteria. 

The current review explicitly excludes (primary) studies that employ single case experimental design (SCED) studies. It is acknowledged that a significant number of studies concerning behavioural interventions in people with autism spectrum disorder, including those relating to ABA, employ SCED methodologies. These small sample studies consider participants as their own control within a tight experimental design, and include “n of 1” studies, ABAB designs (where A is the control phase and B is the intervention), alternating treatment and multiple baseline designs. 

Conduct and appraisal of SCED studies is a specialist area. Quality criteria, appraisal checklists and hierarchies of evidence have been developed specifically for these study designs (Logan et al, 2008), and may vary from those used for group study designs. There is currently no clear consensus within the evidence based practice community about where SCED studies “fit” within group study design hierarchies of evidence, and this is an area of ongoing development and debate. There is a view that the appraisal and evidence ranking of SCED studies and group studies are best considered as “parallel frameworks” (Professor Susan Harris, personal communication, 27 May 2008). 

The Ministries have also contracted another team to conduct a review on the same topic, led by Dr. Oliver Mudford (University of Auckland). This team has particular expertise in SCED studies and will include these in their review (among other study design types).

It is anticipated that the two review approaches, conducted independently and in parallel for the Ministries, will provide complementary, and overlapping streams of evidence-based conclusions. As the two review teams plan to employ different critical appraisal and evidence grading methodologies for considering these overlapping studies, the project provides an opportunity for comparison and cross validation of review conclusions.

To maximise the benefit of having two independent approaches to the review, the two review teams have had only brief contact during the start-up phase to ensure broad agreement on the scope of the reviews, particularly with respect to what interventions to consider under the ABA umbrella, as this is an area of ongoing debate. A meeting was held in June 2008 hosted by the Ministry of Education and attended by key members of both review teams and the Senior Officials Group. The meeting focused on presentations from both teams of their planned methods. A follow-up teleconference was held between representatives of both teams to share search terms, and discuss eligibility of specific interventions. Apart from these meetings, the teams have worked independently, with only brief contact about technical issues prior to study selection. 

The systematic review has taken a broad approach in terms of considering interventions predominantly grounded in ABA, and outcomes that relate to the person with ASD. These included comprehensive outcomes (addressing overall functioning and multiple symptoms over the long term) and focal outcomes (problematic or undesirable behaviours). Whilst recognised as important, outcomes relating specifically to the person with ASD’s family or caregivers were beyond the scope of this review. The review did not systematically consider evidence for the acceptability of, or ethical, economic or legal considerations associated with ABA interventions. 

Objectives

The objective of the review is to consider the effectiveness of ABA interventions for treating people with ASD.

Research Question

What extent are interventions and strategies based on applied behaviour analysis effective in leading to the following outcomes for people with autism spectrum disorders (Ministries of Health and Education 2007): 

  • social development and relating to others;
  • development of cognitive (thinking) skills;
  • development of functional and spontaneous communication which is  used in natural environments;
  • engagement and flexibility in developmentally appropriate tasks and  play and later engagement in vocational activities;
  • development of fine and gross motor skills;
  • prevention of challenging behaviours and substitution with more  appropriate and conventional behaviours;
  • development of independent organisational skills and other behaviours;
  • generalisation of abilities across multiple natural environments outside the treatment setting;
  • maintenance of effects after conclusion of intervention;
  • improvement in behaviours considered non-core ASD behaviours, such as sleep disturbance, self mutilation, aggression, attention and concentration problems.