Nonsymbolic Augmentative Communication for Minimally Verbal Adults with ASD and Severe Intellectual Disability: An Intervention Study

Background: Communication is indispensable for human beings. Individuals with ASD and co-occurring intellectual disability (ID) form a particularly vulnerable group as often no verbal or other symbolic communication is present. Using symbolic communication strategies for someone who is unable to understand the meaning of symbols may lead to high levels of dependence, frustration, or challenging behavior. Nonverbal individuals are dependent on other communication strategies, such as augmentative and alternative communication (AAC). For individuals with ASD and severe to profound ID the common AAC systems are not applicable, because these typically assume symbolic understanding.  

Objectives: Based on a repeated single case design using multiple dependent measures, this study aims to evaluate the effectiveness of individualized nonsymbolic augmentative communication strategies for adults with ASD and ID on individual outcome variables: level of independence, mood, and challenging behavior in daily life.

Methods: Nine participants were recruited from four residential services for adults with ID. Inclusion criteria were: (1) a clinical ASD diagnosis and an ASD classification on a screening questionnaire for ASD in individuals with ID (AVZ-R), (2) a level of severe ID (at least -4 SD scores or a developmental age < 48 months on the Vineland), and (3) a nonsymbolic level of sense-making based on the ComFor, an instrument for the indication of augmentative communication (Verpoorten et al., 2008). Based on the ComFor and video observation, an individualized intervention plan for augmentative communication was designed for one activity. Transitions between activities, different steps or choices within the activity were communicated by recognizable sensations, presenting functional objects or by assembling or matching methods. The single case designs comprised a baseline measurement phase (1-2 weeks) and an intervention phase (1-4 months). The dependent variables, level of independence, mood, and challenging behavior, were measured daily based on an observation form (diary card) for caregivers. A monthly video-taped situation will be coded by an independent observer to measure inter-rater reliability for all three dependent variables and to code treatment fidelity. 

Results: Single case results may be interpreted with the use of two different approaches: visual inspection and statistical analysis. To analyze the data, we used hierarchical linear models, a method for repeated single case designs. For level of independence, all participants showed progression during the intervention phases. The statistical results were significant for seven adults (p < .05). Mood improved significantly (n = 6, p < .05), remained stable (n = 2), or showed an unstable pattern during both baseline and intervention (n = 1). Four participants did not show challenging behavior during this activity; a significant decrease in challenging behavior (e.g., self-injurious behavior) was present in another four participants. 

Conclusions: For all participants, improvement on one or more outcome measures was seen during the activity after individualized nonsymbolic augmentative communication was implemented. However, only a small number of participants were included in this study and a quasi-experimental AB-design was used. Possible influencing factors and suggestions for further research will be discussed.