Autism spectrum disorder (ASD) is a neurodevelopmental disorder that can cause difficulties in communication and social interaction. Naturalistic developmental behavioral interventions (NDBIs) have been tested by clinical trials of behavioral treatments. NDBIs integrate developmental and relationship-based approaches with applied behavioral analysis (ABA) strategies and are implemented in the child’s day-to-day environment, including in play and routine activities where many learning opportunities can be embedded. Among evidence-based practices, the Early Start Denver Model (ESDM) is a representative approach to NDBIs. In addition, ESDM follows comprehensive NDBI principles, grounded in developmental and behavioral science and neuroscientific evidence.
1. Introduction
Autism spectrum disorder (ASD) is a neurodevelopmental disorder that can cause difficulties in communication and social interaction. Children with ASD may maintain the presence of restricted interests and repetitive behaviors
[1]. Furthermore, evidence suggests that reliable diagnosis of children with ASD can be made before the age of 2 years
[2]. An emphasis on very early intervention in several reviews suggests the importance of effective early intervention which may relate to greater possibility of children’s learning and progress
[3]. Accordingly, early intervention is key and leads to better outcomes in shaping the child’s developing brain and is especially crucial for young children with social and developmental disabilities
[4][5].
Early intervention research for ASD has increased dramatically in the past decade. Naturalistic developmental behavioral interventions (NDBIs) have been tested by clinical trials of behavioral treatments
[5][6][7][8][9]. NDBIs integrate developmental and relationship-based approaches with applied behavioral analysis (ABA) strategies and are implemented in the child’s day-to-day environment, including in play and routine activities where many learning opportunities can be embedded
[10][11][12]. In many interventions, natural reinforcement strategies are used which focus on the child’s choices and rewards closely related to the learning activities
[13].
Among evidence-based practices, the Early Start Denver Model (ESDM) is a representative approach to NDBIs. In addition, ESDM follows comprehensive NDBI principles, grounded in developmental and behavioral science
[14][15] and neuroscientific evidence
[16]. Based on ABA and developmental psychology, ESDM is a comprehensive early intervention that aims to reduce the severity of ASD symptom and emphasize in the development of cognitive, social, emotional, and language abilities
[4][17][18]. The model was designed for use with children aged 18–48 months and features a manualized curriculum divided into four levels
[19], each of which targets different developmental areas. Moreover, by emphasizing natural environments and positive relationships to promote children’s learning outcomes, ESDM acknowledges that parents are best placed to implement early interventions in the home setting
[3][18][20][21].
Grounded in Bronfenbrenner’s
[22] ecological systems theory, the theoretical framework indicates that multiple levels of the child’s environment influence child development. The microsystem is the smallest system in which relationships between the child and parent are constructed
[23]. Parents play a crucial role in the early interventions provided to young children with disabilities, helping foster the child’s growth and development
[24]. Parenting a child with autism can be rewarding but also challenging
[25][26][27]. Furthermore, research underscored that parents of children with ASD consistently reported lower levels of parenting-related anxiety, stress, or depression
[5][28]. Indeed, many studies on NDBIs have focused on evaluating the effects of early intervention when delivered by parents. Recent studies have demonstrated that ESDM intervention strategies can be implemented by parents to maximize learning opportunities in daily activities and bridge service gaps; this intervention is known as parent-implemented ESDM (P-ESDM)
[15][28]. Several studies have revealed that (a) parents can learn to implement the intervention techniques with fidelity and (b) doing so results in a range of improvements in child outcomes
[7][8][14][29][30]. Thus, research recommended that parents can plausibly incorporate naturalistic techniques into daily routines in order to accelerate the maintenance and generalizability of treatment gains
[31][32].
P-ESDM is an evidence-based structured approach that teaches parents ESDM techniques such as gaining the child’s attention and motivating them, promoting dyadic engagement and joint activity routines, enhancing verbal and nonverbal communication, and incorporating play skills
[26]. To determine whether improvements in the child’s development result from corresponding changes in the techniques of parent’s interaction, one must take parent’s use of the intervention strategies into account
[33]. Treatment fidelity is defined as “the methodological strategies used to monitor and enhance the reliability and validity of behavioural interventions”
[34] (p. 139). The treatment fidelity is considered acceptable for an adherence of 80% or more
[35]. However, the role of treatment fidelity relates to child intervention response needs further investigation
[36]. Thus, measuring treatment fidelity is crucial for clarifying this relationship.
2. Parent-Implemented Early Start Denver Model for Children with Autism Spectrum Disorder
ESDM is an evidence-based intervention integrating ABA principles
[37]. To address the need for an evidence base that includes research methods evaluating effectiveness, researchers included interventional studies in this entry. All 13 research articles in this entry reported using a quantitative research design, including three that used a multiple-baseline across subjects design
[5][38][39] and one that adopted a single-case nonconcurrent alternating-treatment design
[40]. Of the group studies, one was a nonrandomized controlled trial
[12], four were randomized controlled trials
[15][28][41][42], and three used a quasi-experimental one-group pretest–posttest design
[3][16][17].
Table 1 provide a summary of each study’s (a) child characteristics, (b) intervention intensity and duration, (c) child outcome measures, and (d) parent-related outcome measures and results on parent fidelity.
Table 1. Summary of child characteristics, type of study design, outcome measures, and results of parent fidelity of the included studies.
2.1. Child Characteristics
Of the 13 included studies, 12 provided P-ESDM intervention to a total of 326 children who had received a clinical diagnosis of ASD or were at risk of receiving an ASD diagnosis. In the study by Abouzeid et al.
[17], 6 of the 10 children had received a concomitant diagnosis of global developmental delay (
n = 5) or attention deficit disorder (
n = 1). In Zhou et al.
[12] and Estes et al.
[28], neurological diseases of known genetic etiology (e.g., fragile X) were excluded. By contrast, Vismara et al.
[5] included young children with fragile X syndrome, which is a genetic condition and the leading identified cause of ASD. In six studies
[12][15][17][28][38][39][41][42][43], the ASD diagnosis of the participants was based on the Autism Diagnostic Observation Scale (ADOS)
[44]. Three of these studies
[5][12][28] included a clinical diagnosis of ASD based on the criteria from the Diagnostic and Statistical Manual of Mental Disorders (fourth or fifth edition)
[1][45]. In the study by
[40], participants were assessed using the Modified Checklist for Autism in Toddlers, Revision with Follow-up
[46], whereas in the study by Waddington et al.
[3], participants considered “at risk” of receiving an ASD diagnosis were assessed through the Social Communication Questionnaire
[47]. Participants ranged in age from 12 to 59 months at the start of the intervention.
2.2. Intervention Intensity and Duration
In total, 12 of the 13 studies had P-ESDM training sessions ranging from 1 to 2 h per week over a 10–13-week period. Nonetheless, because neither the P-ESDM nor the community group exhibited significant changes, Zhou et al.
[12] extended the duration of intervention to 26 weeks (two cycles including two ESDM assessments) to evaluate the effects.
2.3. Child Outcomes
The advantages of the P-ESDM intervention in children’s learning outcomes, specifically child behavioral functioning and development, social interaction and communication skills, autism severity, and diagnostic outcomes, were analyzed.
Six research articles reported measures for child behavioral functioning and development
[5][12][15][38][39][41]. These measures were assessed using a variety of instruments, including the MCDI
[48]; MSEL
[49]; Vineland Adaptive Behavior Scales
[50]; PATH CC
[51]; Griffiths Development Scales, Chinese version
[52][53]; and Child Behavior Rating Scale
[54]. All six research articles reported significant improvements over time after the P-ESDM intervention. However, two of the three group studies
[12][38][43] reported no differences in child outcomes between groups.
Eight research articles reported measures for observations of social interaction and communication skills
[3][5][12][15][18][38][40][42]. These measures included expressive and receptive language, verbal and nonverbal responsiveness, spontaneous verbal utterances, imitation skills, symbolic play, social orienting, and joint attention. All the research articles reported positive results for all these outcome measures, except for research articles featuring group studies
[15][42]; these group study articles reported no significant differences in measures pertaining to social and communication skills. In addition, one article
[43] applied the ESDM Curriculum Checklist and the Denver Model commitment coding sheet to examine the effect of the intervention.
Three research articles
[12][15][41] reported measures for autism severity and diagnostic outcomes using ADOS
[44]. These studies reported negative results with no significant differences following intervention.
2.4. Parent-Related Outcomes and the Examination of Parent Fidelity
The advantages of P-ESDM intervention in parent-related outcomes, specifically parent satisfaction, parenting stress, coaching experience, parent engagement, parent-implemented goals, and parent fidelity, were analyzed.
Nine research articles
[3][12][15][17][18][39][40][41][42] reported positive results in that most of the parents felt satisfied or agreed that they would recommend this approach to others. Moreover, these studies used questionnaires or measures that evaluated the parents’ willingness to participate in the program, such as the Treatment Acceptability Rating Form-Revised questionnaire
[55] and the Intervention Evaluation Form (University of Washington, unpublished
[41]).
Several research articles evaluated additional parent-related outcome measures. Two research articles
[28][42] reported positive results for parenting stress based on the measures included in the Parenting Stress Index-Short Form
[56] and the Questionnaire of Resources and Stress
[57]. Three research articles
[3][5][17] reported positive ratings for coaching experience and relationship with the trainer. Three research articles
[5][38][39] reported positive results for parent engagement using the Maternal Behavior Rating Scale
[54] or measures developed by the researcher
[5].
Ten of the 13 studies examined parent fidelity in implementation
[3][5][15][17][28][38][39][40][41][42]. The measures included the ESDM Fidelity Rating System
[19] and the P-ESDM Fidelity Tool
[58]. All these research articles reported improvements in interaction skills over the 12-week period of the P-ESDM. However, most of the parents in only 50% of the studies
[3][38][39][40][42] achieved the standard benchmark (at least 80% at posttest) for acceptable fidelity using the ESDM.