Linguistic profile of adults with prader-willi syndrome: evidence from a narrative task

Research on language has recently focused on the nature of linguistic skills that individual with mental retardation in genetic disorders may exhibit, trying to demonstrate that some language processes may be preserved and function independently of mental retardation (MR) and of other cognitive systems. The aim of this study was to highlight the level of development and organization that adults with Prader-Willy (P-W) syndrome may reach on oral production and the possible relationship with general cognitive development. We studied a group of 12 young adults with P-W syndrome (mean age 24.3), with mild to moderate mental retardation, as defined by CPM and TIB. Subjects were asked to produce a story, depicted on connected pictures. The extracted narrative sample (mean number of words was 305.7) was analyzed along a set of measures: speech rate, morphological measures ( e.g., open/closed class, noun/ verb ratio, token/types ratios) and structural measures (e.g., sentences types and frequencies, embedding index). Speech repairs were also analyzed. Our subjects, divided according to MR level, showed marked differences both qualitative and quantitative in speech rate, morphological and structural measures. Results seem to suggest that young adults with P-W syndrome may have developed some complex linguistic processes and mechanisms and that general cognitive skills might interfere on their ability to activate and extensively use these knowledge during narrative speech production.