Abstract: This review included two randomised controlled trials involving 38 children (20 boys, 18 girls), aged 15 to 96 months, and their mothers. All children had developmental disabilities; 10 had motor disorders, but it was unclear if these motor disorders affected their gestural, vocal or verbal communication. Mothers attended eight group training sessions over 11 to 12 weeks and received two or three home visits. Outcomes were assessed immediately after training. We found no report of longer-term follow-up. One study took place at an intervention centre in Canada and the other in South Korea. Both studies recruited small numbers of participants from single centres. Since it is not possible to blind participants attending or therapists providing training to group allocation, we considered both studies to be at high risk of performance bias. We also rated one study at high risk of attrition bias, and both studies at low risk of reporting bias. There was very low-quality evidence for all outcomes assessed. There was no evidence of an effect of training for children's initiation of conversation or engagement in joint attention during interaction with their mothers. Mothers who received training became more responsive to their children's communication, but there were no differences in the extent to which they controlled conversation by directing their children. Missing data meant that we were unable to evaluate the effects of training on children's frequency of communication, frequency of spoken language in conversation, speech production, or receptive or expressive language development. There were no effects on maternal stress. We found no reports of the effects of parent training on children's use of individual communication skills, such as asking questions or providing information, on their generic participation or adverse outcomes. Neither did we find reports of mothers' satisfaction with treatment, its acceptability or their compliance with it. There is only limited, very low quality evidence that parent-mediated communication interventions may be associated with improvements in interaction between mothers and their preschool children who have motor disorders. The indirectness of the study samples and high risk of bias in the included the studies significantly limits our confidence in the evidence, as do issues with study design and lack of detail in results. It is not clear if training has been tested with children whose motor disorders limit the consistency and accuracy of movements underpinning spoken or gestural communication. Some speech and language therapists currently provide communication training for parents. Further research, with larger numbers of children whose movement disorders affect their speech and gestures, coupled with detailed reporting of children's baseline skills, is needed to test whether communication training for parents can help them to promote the communication development of their young children with movement disorders.

Plain-language summary: We searched for studies published up to July 2017. We found only two studies that reported the effects of parent communication training; one study took place at an intervention centre in Canada, the other in South Korea. The studies involved 38 children (20 boys, 18 girls), aged 15 to 96 months, and their mothers. Both studies compared parent communication training with no intervention for communication problems. Mothers attended eight group training sessions 11 to 12 weeks with two or three home visits. The studies involved children with a range of developmental difficulties; most had intellectual disability, 10 had movement disorders (cerebral palsy). However, the extent to which children's movement disorder affected their communication was not clear; all children appeared to have good use of their hands for gesture and pointing, and impairment of speech was not reported. Results were assessed immediately after training. We found no report of results at a later date (longer-term follow-up). In the two small studies, it appears that mothers may have responded more frequently to their child's interaction following parent-mediated communication training. However, there was no associated reduction in mothers' directiveness (such as their use of commands) in conversation and no change in maternal stress. For the children, we found no evidence for change in children's initiation of conversation or of joint attention in interaction with others. Studies did not report any negative effects of training, mothers' adherence to guidance within the training or the acceptability of the programmes. We were not able to evaluate the effects of parent-mediated communication intervention and frequency of children's communication, their use of spoken language in conversation with their parents, their speech production or their language development because the data were not available. We have no reports of children's development of individual communication skills, such as learning to ask questions, and no reports of defects of the intervention on their generic participation or harms arising from the intervention. Finally, we found no reports of maternal satisfaction with the treatment. We judged the evidence from the included studies to be of very low quality because of issues with study design and a lack of detail in the results presented, and because it was not clear whether children's movement disorders affected their communication. Research with larger numbers of families of children whose movement disorders affect their speech and gesture is needed, to test whether communication training for parents can help them to promote the communication development of their young children with movement disorders.