Current Evidence Base on Interventions and Parent Education for Minimally Verbal Children with ASD

In a systematic review, we summarized current evidence on interventions for nonverbal and minimally-verbal children with autism and on parent education in intervention studies with nonverbal and minimally verbal children with autism.

Intervention for Non-verbal and Minimally-Verbal Individuals with Autism



Most children diagnosed with ASD will present with late onset verbal communication, and at least one third of these children will remain minimally or completely nonverbal throughout their lifespan, speaking few or no words. Challenges with verbal language can negatively affect many areas, including socialization, academics, independent living and employment. The objective of this paper was to systematically review interventions for the treatment of nonverbal and minimally verbal individuals with ASD. This review exclusively selected studies that targeted verbal communication in minimally and nonverbal individuals diagnosed with ASD. The interventions provided, the outcomes of these interventions, measures used to assess change, and pre- post measures were included.


What is the current evidence base for interventions for non- and minimally verbal individuals with Autism Spectrum Disorder (ASD)?


A literature search was conducted through ProQuest (Mendeley reference manager). Articles were extrapolated from seventy data bases. Databases surveyed included Medline, Periodicals Archive Online, Periodicals Index Online, PRISMA Database, ProQuest Central, PsycARTICLES and PsycINFO. The publication span entered was 1960 to 2018. Reliability for coding was examined and was uniformly above 90% concordance.


Our search yielded 2,007 articles, of which 29 studies met our inclusion criteria. Inclusion criteria included: (1) Research Design: Studies that involved systematic, experimentally controlled investigations, such as randomized controlled trials, quasi-experimental designs, and single-case designs; (2) Diagnosis: only studies that included minimally verbal, nonverbal, and preverbal participants diagnosed with ASD were included; and (3) Targeted verbal communication: the goal of the intervention was to initiate or improve verbal communication, including the production of words, word attempts, or sounds. This review found that there was a wide variety of interventions provided, comparisons across interventions were lacking, and dependent measures varied considerably.


Presently, pediatricians and service providers are unable to provide evidence-based treatment recommendations regarding speech and language interventions for non- and minimally verbal individuals with ASD. Limited evidence suggests that verbal-focused treatments in natural settings with parent participation is effective, as research regarding the most effective and efficient interventions for this high need group is lacking. Lack of uniformity in regard to dependent and pre- post measures, participant ages, and description of interventions implemented make comparing outcomes across studies difficult. Uniform standards for identifying MV and NV children with ASD is needed in future studies and additional details on the intervention procedures in futures studies is also needed.


Koegel LK, Bryan KM, Su PL, Vaidya M, Camarata S. (2019). Intervention for Non-verbal and Minimally-Verbal Individuals with Autism: A Systematic Review. Int J Pediatr Res 5:056.

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The purpose of this systematic review was to identify parent education procedures implemented in intervention studies focused on expressive verbal communication for nonverbal (NV) or minimally verbal (MV) children with autism spectrum disorder (ASD). Parent education has been shown to be an essential component in the habilitation of individuals with ASD. Parents of individuals with ASD who are NV or MV may particularly benefit from parent education in order to provide opportunities for communication and to support their children across the life span.


ProQuest databases were searched between the years of 1960 and 2018 to identify articles that targeted verbal communication in MV and NV individuals with ASD. A total of 1,231 were evaluated to assess whether parent education was implemented. We found 36 studies that included a parent education component. These were reviewed with regard to (a) the number of participants and participants' ages, (b) the parent education program provided, (c) the format of the parent education, (d) the duration of the parent education, (e) the measurement of parent education, and (f) the parent fidelity of implementation scores.


The results of this analysis showed that very few studies have included a parent education component, descriptions of the parent education programs are unclear in most studies, and few studies have scored the parents' implementation of the intervention.


Currently, there is great variability in parent education programs in regard to participant age, hours provided, fidelity of implementation, format of parent education, and type of treatment used. Suggestions are made to provide both a more comprehensive description and consistent measurement of parent education programs.


Koegel, L. K., Bryan, K. M., Su, P. L., Vaidya, M., & Camarata, S. (2020). Parent education in studies with nonverbal and minimally verbal participants with autism spectrum disorder: A systematic review. American journal of speech-language pathology, 29(2), 890-902.

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