Intervention for Non-verbal and Minimally-Verbal Individuals with Autism: A Systematic Review

Background: 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 prepost measures were included. Question: What is the current evidence base for interventions for nonand minimally verbal individuals with Autism Spectrum Disorder (ASD)? Methods: 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. A complete list of all databases included is available on ProQuest (http://tls.search.proquest. com/titlelist/jsp/list/tlsSingle.jsp?productId=10000255). The publication span entered was 1960 to 2018. Reliability for coding was examined and was uniformly above 90% concordance. Results: 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 were a wide variety of interventions provided, comparisons across interventions were lacking, and dependent measures varied considerably. Conclusions: Presently, pediatricians and service providers are unable to provide evidence-based treatment recommendations regarding speech and language interventions for nonand minimally verbal individuals with ASD. There is limited evidence that verbal-focused treatments in natural settings with parent participation is effective, research regarding the most effective and efficient interventions for this high need group is lacking. Lack of uniformity in regard to dependent and prepost measures, participant ages, and description of interventions implemented make it difficult to compare outcomes across studies. Additional research using uniform standards for identifying MV and NV children with ASD and for details on the intervention procedures in each study is needed.