A Systematic Review of Theory of Mind Based Interventions for Autism Spectrum Disorder

Background: The ’Theory of Mind’ model suggests that most people with autism spectrum disorder (ASD) have a profound difficulty understanding the minds of other people - their emotions, feelings, beliefs and thoughts. As an explanation for some of the characteristic behaviours of people with autism spectrum disorder (ASD), this model has had a significant influence on research and practice. It implies that successful interventions to teach ToM could in turn have far-reaching effects on behaviours and outcome.

Objectives: To review the efficacy of interventions based on the ToM model for individuals with ASD.

Methods: We searched 8 international databases including MEDLINE and PsycINFO, as well as performing hand searches of relevant journals, conference proceedings and making contact with authors in the field. Studies were selected on the basis that they reported on an intervention linked to ToM in one of four clearly-defined ways: designed to test the ToM model; designed to teach ToM; designed to teach precursor skills of ToM (e.g. emotion recognition, joint attention); based on or inspired by ToM models of autism. The replicability of these definitions was tested in a pilot by 3 naïve raters. In addition, included studies presented new randomised controlled trial data from participants with a confirmed ASD diagnosis.  Studies were selected and data extracted by two researchers independently and a third expert arbitrated.

Results:   Twenty-two randomized controlled trials were included in the review (n=695).  Studies were highly variable in their country of origin, sample size, participant age, intervention delivery type, and outcome measures. Risk of bias was variable across categories. Further complexity in interpreting results was introduced by the wide range of measures used within each outcome category and by the mixed results from these measures. Studies were grouped into four main categories according to intervention target / primary outcome measure. These were: emotion recognition studies, joint attention and social communication studies, imitation studies, and studies teaching ToM itself. Meta-analyses indicated that interventions targeting emotion recognition had a positive effect on the target skill (mean increase of 0.66 points, z=3.19, p<.001) and that therapist-led joint attention interventions can promote production of more joint attention behaviours within adult-child interaction (mean increase of 0.55 points, z=2.45, p=.01). However there was also a lack of effect of intervention on joint attention initiations as measured using a standardised assessment tool (mean increase of 0.23 points, z=0.63, p=.53). No adverse effects were apparent.

Conclusions: While there is some evidence that ToM, or a precursor skill, can be taught to people with ASD, there is little evidence of maintenance of that skill, generalisation to other settings, or developmental effects on related skills. Furthermore, inconsistency in findings and measurement means that evidence has been graded of low quality and we cannot be confident that suggestions of positive effects will be sustained as high-quality evidence accumulates. Further longitudinal designs and larger samples are needed to help elucidate both the efficacy of ToM-linked interventions and the explanatory value of the ToM model itself.