This review found evidence of a significant effect of the Sonas programme on communication ability among people with severe dementia. However, it is difficult to compare the outcomes of the studies as they vary in terms of sample size, length of intervention period, frequency and delivery. Furthermore, while there is training for people who wish to deliver the Sonas intervention, some studies involved the delivery of Sonas sessions by untrained staff. Some studies did include persons without dementia. A comparison is also difficult because several of the studies have methodological weaknesses and no measure used for adherence to the Sonas intervention.publishedVersio
