A longitudinal study of cognitive skills and communication behaviours in children with Rett syndrome.

Changes in the cognitive, communicative and interactive development of a group of six girls with Rett syndrome (three younger and three older) were documented over a 3-year period. All six maintained a profound level of intellectual performance and a preintentional level of communication in which caregivers assigned meaning to the girls' limited behaviours. However, marked individual variation was noted in both cognitive and social interaction skills. The study supported the notion of an increased perception of social interactiveness by the caregivers over time. The development of means-end behaviour, in particular, seems closely linked with the measured increase in behaviours inferred as communicative. However, the results also show that factors such as cognitive level, physical status and educational intervention may be related to this perception.