Uno studio longitudinale sullo sviluppo linguistico di bambini gemelli e singoli nati nel secondo anno di vita

Several studies reported that twins have delayed language development compared to singletons. The difference is more evident at young age, but the delay becomes less stable with age increase. The present study aimed at analysing twin children’s linguistic development in the second year of life, comparing them to singleton children. Twin group was composed by 10 sets of twins (6 MZ, 4 DZ; 13 M, 7 F); singleton group included 20 children (13 M, 7 F). All children had a birth weight appropriate for gestational age and were free from neurological damage peri-natal ascertainable or belonged to families issues. Twins and singletons were longitudinally examined through a parent report questionnaire (PVB Italian version of the McArthur-Bates CDs). Children were observed bimonthly at the age of 16, 18, 20, 22 and 24 months. At first age children were assessed either on word comprehension and word and gesture production. At next ages the measures considered were word and sentence production. The results showed a significant increase of word production for both children group even if twins produced significantly less words than singletons at 16 and 18 months. In the next stages twins got near singletons but some differences were still evident with regard to lexicon composition and phrase production. During the period of observation, twins have been using few verbs and predicates respect to singletons. Considering sentence production, twins used fewer phrases than singletons at each age, and only at 22 months of age started to produce sentences with functions. Singletons were more advanced than twins because they produced these types of sentences already at 18 months of age. The results highlight a late language development rather than a delay in twins therefore they need constant monitoring from infancy to school age.