As part of our AT-node project, we regularly search the literature on the use of alternative access interfaces by people with disabilities. Here’s an interesting article from 2019 that appeared in our latest search: ‘Non-medical interventions for individuals with Rett syndrome: a systematic review‘ by Annika Amoako and Dougal Hare, published in the Journal of Applied Research in Intellectual Disabilities. In this post, I’ll share what the authors found related to assistive technology as an intervention for Rett syndrome.
Overview of the systematic review study
The goal of the study was to systematically review the quality and efficacy of all non-medical interventions that have been investigated for Rett syndrome, as described in the published literature. These interventions include assistive technology and AAC communication technology. The authors conducted a careful review, following PRISMA guidelines, and found 22 studies meeting their criteria. The full article summarizes all 22 studies and assesses the quality of each one. Of those, 13/22 were scored as being of acceptable quality (based on their QATCS score).
In this post, we’ll cover the 8 studies that focused on assistive technology (AT) or AAC technology interventions. (All 8 were judged to have acceptable quality.) We’ll try to answer the following question: To what extent is there clear evidence regarding the efficacy of these interventions for individuals with Rett syndrome?
Summaries of the 8 studies
Systematic review authors Amoako and Hare summarized each study in their Table 2. I’ve extracted that information and reproduced it here, as a separate table for each of the 8 studies that focuses on AT as an intervention in Rett syndrome. The study number in the table heading matches what’s shown in Amoako and Hare’s Table 2.
| Variables | IV – storybook intervention DV – communication ability |
| Design | Multiple baseline |
| Measures | Storybook interactions coded by communication mode and communication act (e.g., use of picture symbols and speech-generating devices to label pictures) |
| Intervention | Introduction of a variety of assistive technologies on the storybook reading and communicative interactions. Parental training of storybook interactions. |
| Sessions | Families attended 5 monthly information sessions across 4 months. |
| Results | Substantial increases in frequency of symbolic communication and labelling were reported in all 6 participants. No effect size or statistical tests completed. |
| Variables | IV – assistive technology DV – learning |
| Design | Multiple-probe design |
| Measures | Symbol set identification |
| Intervention | Use of individualized computer-based AAC system (choice of picture, symbol, or word, using eye gaze and moving nose or head) |
| Sessions | Session lengths were variable. Unclear info regarding intervention dosage. |
| Results | Steady learning curve across symbol sets and a partial retention of knowledge through maintenance probes. Suggests that girls with Rett syndrome can match spoken words to symbols when provided with meaningful instruction. However, some baseline results also improved, so improvement should be interpreted cautiously. No effect size or statistical tests completed. |
| Variables | IV – assistive technology DV – performance, happiness, and reduction in stereotypes |
| Design | Multiple-probe design |
| Measures | Frequency of microswitch activation, indices of happiness, indices of stereotyped behaviors |
| Intervention | Assistive technology (microswitch) for five minutes, 3-4x per day over six months |
| Sessions | 3-4 sessions per day (5 min each), 4 days per week for six months |
| Results | Increase in performance of microswitch use and of indices of happiness. Decrease in stereotyped behaviors for both participants. Indices for happiness difference for one participant were reported on and statistically significant (p<.01). |
| Variables | IV – PECS and VOCA DV – communication |
| Design | Alternating treatment single-case design |
| Measures | Number of items requested and chosen independently, indices of happiness and stereotyped behaviors |
| Intervention | PECS sessions and VOCA sessions |
| Sessions | 2-4 sessions per day (10 min each), 5 days per week for four months |
| Results | Increase in requesting and choosing items (significant for all three participants at p<.01). Increase in indices of happiness. Decrease in stereotyped behaviors. |
| Variables | IV – assistive technology (microswitch) DV – microswitch responses and level of happiness |
| Design | ABAB |
| Measures | Level of microswitch response and objective measures of happiness |
| Intervention | Microswitch-assisted technology |
| Sessions | 1 session per day (5 min long), 5 days per week across 11 total sessions |
| Results | Increase in microswitch responses and level of happiness for both participants. No effect size or statistical tests completed. |
| Variables | IV – assistive technology (sensors and personal computer) DV – responses and stereotyped behaviors |
| Design | Multiple-probe design |
| Measures | Requests for preferred stimuli, Happiness indices, Intervals of stereotypic behaviors |
| Intervention | Assistive technology (2 different microswitches) |
| Sessions | 2-4 sessions per day (10 min each), 4 days per week across 225 total sessions (over six months) |
| Results | Increase in adaptive responses and happiness indices. Reduction in stereotypic behaviors. All differences between baseline and intervention phases were statistically significant, for the two participants involved (p<.01) |
| Variables | IV – AAC intervention (speech-generating device with eye gaze or touch screen technology) DV – AAC responses |
| Design | Concurrent multiple-baseline design |
| Measures | Independent accurate selection (via pressing or eye gaze) of target requests |
| Intervention | Use of speech-generating device (SGD) to increase aided AAC using either pressing or eye gaze to select preferred item |
| Sessions | 3-6 sessions per day (5-15 min each), 1-2 days per week across 6-8 months |
| Results | Acquisition of requesting skills for one participant, which were sustained. Increased skills for second participant, but the skills were not sustained when prompt was faded. No effect size or statistical tests completed. |
| Variables | IV – parent-implemented communication intervention with remote coaching via telehealth DV – AAC responses |
| Design | Adapted multiple-probe design with an embedded ABAB design |
| Measures | AAC responses (hitting a microswitch to say “more”) and individual idiosyncratic responses (e.g., hitting the tray of high chair) |
| Intervention | Parent-implemented functional communication training with telehealth as a service delivery mechanism |
| Sessions | Parent communication training: Up to 7 sessions per day (5 min each). No info on how many days. |
| Results | AAC response was learnt across three contexts, but the participant did not retain the learning of responses. No effect size or statistical tests completed. |
Some thoughts on the 8 studies
Can we draw any conclusions?
Amoako and Hare have done the hard work of exhaustively searching the literature for us, so they’ve given us a great gift. It’s not easy, though, to simply look at the summaries of those 8 studies and draw clear conclusions. In some cases, we want more information: e.g., what task were participants doing with their microswitch (Study 16)? How were individuals accessing their AT (all studies except 7 & 21)?
And for all studies: How large were the changes? What was the impact on daily life, if any, outside of the study context? We may be able to find the answers to these types of questions by digging into each article, but that can be tough when papers are hidden behind pay walls (as is the case for all but one of the above studies). So we may not have all the information we’d like to have about these studies, in order to draw solid conclusions.
However, given that the studies passed Amoako and Hare’s criteria for acceptable quality, it seems reasonable to examine the results (with caution) and see what themes emerge.
What conclusions can we draw?
- There is a reasonably strong evidence base supporting the use of communication interventions for individuals with Rett syndrome. All 8 studies demonstrated a positive outcome for the participants, in areas such as making requests, learning symbols, happiness, and behavior.
- Half of the studies involved a computer-based AAC system as part of the intervention (Studies 5, 7, 18, 21), and half involved a single-output microswitch (Studies 16, 19, 20, 22). Only two studies specified the access method used: eye-gaze (7, 21), moving nose or head (7), or touchscreen press (21).
- Parents can be successfully involved in delivering these interventions (5, 22)
- Retention of learned responses may be a challenge (7, 21, 22)
Opportunities for the future
Studies always conclude with the “need for future work,” a phrase that has earned its status as a cliché. It’s true here as well. While the work reviewed here suggests a positive impact of assistive technology for individuals with Rett syndrome, there are many knowledge gaps remaining to be filled. We need to know more about the types of interventions most likely to be effective, interventions that are likely to be more durable, the types of training that work best, methods of transferring new skills into daily life, and so on. And the results here involve a total of 21 individuals with Rett syndrome, highlighting the need for larger participant numbers.
These 8 studies provide some snapshots of effectiveness under certain conditions, enough to encourage us, as a field, to continue the hard work required to round out the picture with additional studies. Over time, even small N studies can cumulate to build knowledge that will benefit practitioners as well as individuals with Rett syndrome.
I hope this information is useful. If you’d like a copy of Amoako and Hare’s systematic review, please let me know (just comment below or send your email address to me at hhk@kpronline.com).
Finally, many thanks to Rettsyndrome.org, PRC-Saltillo, and the individuals pictured for permission to use the photo in this post.