<p><strong>Autism is a form of neurodivergence characterised by differences in social communication, the presence of passionate interests, and a preference for predictable activities and routines. Early support programmes can enhance the development of Autistic children and can lead to improvements in areas such as communication, play skills, cognition, and social engagement. Naturalistic developmental behavioural interventions (NDBIs) are a promising early support approach. Parent-mediated programmes, including parent-mediated NDBIs, are also a promising approach for supporting the learning and development of Autistic children. The rationale for parent-mediated supports includes the possibility that parents are well-placed to deliver teaching and learning opportunities throughout their children’s every-day routines, which may lead to greater consistency of learning and thus improved child outcomes. There may also be benefits for parents who participate in these programmes including improving parental stress and self-efficacy, as well as parent sense of competence and family cohesion. Additionally, parent-mediated approaches are a time and cost-effective alternative to intensive clinician-implemented supports. Despite the theoretical rationale for such approaches however, parent and child outcomes from individual parent-mediated NDBIs are variable. Therefore, more research is needed to understand the impact of parent-mediated NDBIs, and to evaluate adaptations that may improve the fit between parent and child needs, and the models that aim to support them. Tiered programmes or “stepped care” approaches may be an appropriate way to individualise the supports that families receive, while prioritising efficient service delivery. In a multi-tiered approach, individuals receive low-intensity support in initial tiers, and can then step up to higher levels of support if needed. This thesis consists of three main components. The first component was a systematic literature review of single-case evaluations of parent-mediated NDBIs. That review reports on study quality, participants, programme characteristics, aims, and outcomes across 17 studies published in the last 10 years (2014-2013). The second component was an original empirical study using a single-case multiple baseline design. The aim was to evaluate the efficacy of a two-tiered parent-coaching programme based on the Early Start Denver Model (ESDM) – a comprehensive NDBI – for seven Autistic boys (aged 36-52 months) and their parents (5 mothers, 2 fathers). After a 10-week group coaching programme (Tier 1), all parents had increased their use of ESDM strategies. Changes in parent fidelity during the additional individual coaching (Tier 2) were mixed, but all parents maintained higher than baseline levels of fidelity. There were positive changes in parent stress levels pre- post-coaching. Across the two-tiers, positive results were found for most children’s levels of engagement, imitation, and communication. There were significant positive relationships between parent fidelity and both child engagement and child functional utterances.</strong></p><p>The third component was a qualitative study involving reflexive thematic analysis to analyse parents’ perceptions of participating in the two-tiered support programme. Four key themes and 13 subthemes were developed. The themes centred on (a) programme accessibility and participation, (b) experience of the two-tiered coaching process, (c) commitment and perseverance, and (d) outcomes. Several parents described barriers to accessing this programme including cultural considerations. Parents described many benefits of the two-tiered coaching design, and both strengths and challenges regarding the programme content, duration, process, coaching approach, and child experience. Parents reported both barriers and facilitators to implementing the programme strategies at home. Overall, parents were mostly satisfied with the programme outcomes, citing improvements for their child, themselves, and their families. Together, the results from these studies provide preliminary support for the feasibility, acceptability, and effectiveness of delivering parent mediated ESDM (P-ESDM) in groups, and for individualising supports in additional tiers for some families. More research is needed to see if these findings are replicable with larger sample sizes, and through community rather than researcher implementation. It would also be valuable to explore different approaches to customising supports in more intensive tiers, to better meet the unique needs of individual families.</p>
